The Actual Situation of Korean Wartime Labor at the Sado Gold Mines

Ryosuke Nagatani (Researcher, Historical Awareness Research Committee)


                 The Actual Situation of Korean Wartime Labor at the Sado Gold Mines


  1. Primary Documents Concerning the Sado Gold Mines

At present, the following six documents constitute all known primary sources regarding the Sado gold mines:

(1) Hirai Eiichi’s edited History of the Sado Mines (Volume II) (1950)

(2) The Sado mining operations’ document “Concerning Korean Personnel Management” (June 1943)

(3) The Japan Mining Industry’s Survey Report on Korean Laborers (December 1940)

(4) “Survey Results on Accrued Wages Payable to Repatriated Koreans” (included in Survey Report on Korean Assets in Japan and “Economic Cooperation and South Korea 105: Accrued Wages payable to Koreans”

(5) A list of the tobacco rations distributed to Koreans

(6) An article on the Sado mines, published in the Special Higher Police Monthly Report.

As the first two documents have already been dealt with at length in Nishioka’s presentation, I would like to omit them from my own. (3) is a survey conducted by the Japan Mining Industry across 84 of Japan’s principal mines, which recorded the treatment of Korean workers. (4) is an official document regarding an investigative report on the unpaid wages and deposits of Koreans after the war, the “Survey Results on Accrued Wages Payable to Repatriated Koreans” of which concerns the Sado mines. The records show that outstanding wages and deposits for 1,140 workers only amounted to \231,59.59 JPY. (5) is a list of the Koreans who resided in the four Soai dormitories and the company housing managed by Sado mining operation at the time. Compiled in 1943 and 1945 over the course of the company’s distribution of cigarettes to laborers, the list contains the names, dates of birth, and travel-related information of 463 Koreans, albeit only partially. (6) The Special Higher Police Monthly Report describes three cases of disputes involving Koreans as well as five cases of desertion that occurred at the Sado mines during the war.


  1. The Contents of Previous Research

Typical examples of previous research on Korean workers at the Sado mines include A Comprehensive History of Niigata Prefecture: Modern History Volume 3 (hereinafter abbreviated as the History of Niigata Prefecture), published by Niigata Prefecture in 1988, and A Comprehensive History of Sado Aikawa: Modern History (hereinafter abbreviated as the History of Sado Aikawa), published by Aikawa Town in 1995. The former features the paragraph “Forcibly Mobilized Koreans”, and explains that Koreans were forcibly mobilized from the period of recruitment that commenced in 1939. It also states that the Sado mining operations discriminated against Korean workers on the basis of their ethnicity, forcibly renewing contracts and assigning Koreans to hazardous jobs such as rock drilling and transportation. These allegations are based on the second document, “Concerning Korean Personnel Management”.

The latter also echoes the sentiment that Koreans were forcibly mobilized, citing the testimony of Souji Sugimoto (a former labor section staff member at the Sado mines) in arguing that the recruitment of Koreans was started as a means of ameliorating the gap in the labor force caused by silicosis infection among many Japanese pit workers and the ceaseless drafting of young, Japanese workers into the army.

In terms of individual papers, there are those by Shigeru Nagasawa and Yasuji Sato, while Teizo Hirose’s “Korean Laborers and the Sado Mines (1939-1945)”, published in the third issue of Proceedings of Niigata University of International and Information Studies Faculty of Informatics and Sciences in 2000, provides a detailed summary. In addition to the aforementioned primary sources, Hirose also references the previous studies by Nagasawa and Sato as well as contemporary newspapers from Niigata Prefecture in his examination of the circumstances of Korean laborers at the Sado mines concluding that Korean workers were coerced into working and suffered racial discrimination.

Hirose points to the fact-as indicated in both the History of Sado Aikawa and “Concerning Korean Personnel Management”-that the percentage of Koreans engaged in dangerous underground work exceeded that of Japanese laborers as evidence of racial discrimination. Furthermore, he cites Sugimoto’s testimony concerning silicosis in postulating that the aim of hiring Koreans was not only to compensate for the labor shortage but was also intended to cull silicosis infection in Japanese workers. On this point, Hirose cites Ken Saito’s 1944 study “Investigative Study and Addendum on Silicosis”, which examined silicosis at the Sado mining operations, and found that many laborers engaged in drilling, transportation, and pillaring had inhaled the average amount of dust that causes the disease. Koreans represented a significant proportion of the workers in these occupations, and Hirose essentially considers this study to be a survey of Koreans.

On the subject of Korean wages, Hirose indicates that the salaries of the “contract system” benefited Japanese workers more than Koreans, who were former farmers, and that the wages they received once the cost of tools was deducted were meager. He also presents the company’s forced renewal of Korean contracts once the initial period of two or three years had elapsed as evidence of forced labor.


  1. Collating the Contents of Previous Research and Cross-checking Primary Sources

Though I have just provided a brief explanation of the prior research on the Sado mines, it is important to observe that no specific consideration has been given to the forced mobilization of Koreans. The History of Niigata Prefecture offers no academic discussion in arbitrarily stipulating that everything from the period of recruitment which began in 1939 to the conscription of 1944, constitutes “forced mobilization”. This pragmatic trend was largely spawned by the publication of Park Kyung-sik’s Record of the Forced Mobilization of Koreans (Mirai-sha Publishers) in 1965, which established the misconception that everything from recruitment to conscription was “forced labor” as “common knowledge” within Japanese academia, despite never having been sufficiently verified.

However, there exist many primary sources that deny such notions of forced mobilization. For example, the memoirs of Chuemon Ishido (included in Eidai Hayashi’s edited Fourth Compilation of Historical Documents on the Wartime Forced Mobilization of Foreigners Vol. 1, Akashi Shoten, 1991), in which he depicts the recruitment situation at Naoshima Smelter and Refinery (a Mitsubishi affiliate, as were the Sado mines), Koreans who failed the job interview (March 20, 1940), Koreans who assumed a different identity in order to secure a job (March 26, 1940), as well as the image of Koreans driving in full song, “as merry as students on a school trip” (March 27, 1945). The seemingly blite inclusion of such a text in historical records pertaining to forced mobilization is indicative of just how ill-founded the “forced mobilization” theory really is.

Furthermore, the author responsible for the chapter “Forcibly Mobilized Koreans” in the History of Niigata Prefecture is Yasuji Sato. Sato has also contributed to the journal Studies in the History of Korean Residents in Japan, launched by Park Kyung-sik, reflecting his status as a proponent of the “forced labor” theory. In other words, this was not a prefectural history written by a neutral third party.

It should be noted that in the History of Sado Aikawa, primary sources and testimonies are conflated. It is only natural that discrepancies may arise between the contents of extant historical documents from the time and testimonies recounted years later. In the text, Sugimoto states that “a total of 1,200 people” were working at the Sado mines when recruitment ended in March 1945. However, in Hirai’s History of the Sado Mines (Vol. II), a primary source, the number is given as 1,519; 300 is certainly no slight error. Elsewhere, Sugimoto says that recruitment first began in February 1939, but Hirai and “Concerning Korean Personnel Management” describe it as having commenced in February 1940. Whether or not the accuracy of Sugimoto’s recollections has been vitiated with the passing of time necessitates verification.

Additionally, it is also mentioned that, in his recollection, the head of the labor division at the time identified the extreme prejudice rampant among a certain section of the labor division staff as having been the cause of disputes involving Koreans at the Sado mines. However, crucial information as to the identity of this person has been omitted. Since Sugimoto would have used his name, it is highly possible that this “head of the labor division at the time” was a different person. It is reckless to accept the recollections of an anonymous individual unquestioningly.


  1. Assignment of Underground Labor and Incidence Rate of Silicosis

The use of primary sources by previous research in its surmise that the Sado mines were the site of forced labor is typified by silicosis and the allocation of Korean workers to underground work. I would first like to examine whether the assignment of drilling and pillaring to many Koreans may reasonably be considered discrimination.

Sugimoto focuses his argument on silicosis, but the fundamental issue was the labor shortage caused by the successive conscription of Japanese men into the army, meaning that Korean men were the only ones left to assign this work. Compounding this was the population decline in Niigata Prefecture, a corollary of the migration policy to Manchuria initiated prior to the draft. According to Yamakawa Publishing’s History of Niigata Prefecture (1998), the number of colonist groups dispatched from Niigata Prefecture to Manchukuo in China between 1937 and May 1945 was more than 12,600, making it the fifth-largest number nationwide. Also, since the bedrock of the Sado mines is hard, there was little risk of cave-in; “Yawaragi”, a traditional art passed down in Sado, is a Shinto ritual in which workers sing before a shrine to pray for the stones to soften.

Regarding silicosis, although Hirose considers Saito’s dissertation to be a survey of Korean workers, Saito states in his dissertation that it takes at least four years and 11 months for the first phase of the disease to develop. Koreans were only contracted to work for two or three years, and even if their contracts were renewed, it is unlikely that many continued to work for five years. According to Kiyonobu Tanno’s paper “On the Mental Function of Silicosis”, published in the Niigata Medical Journal in 1953, it is only from stage II of the disease that silicosis becomes severe, and no clear distinction between silicosis stage I and healthy subjects can be recognized except in the case where a workload is applied. As can be seen from Table 1, it is reasonable to infer that the target of the study was not, in fact, Koreans but Japanese, considering the length of service.

Furthermore, in 1954, Kiyonobu Tanno published “Silicosis Incidence Rate and Progression by Occupation and Years of Service” (included in Niigata Medical Journal Vol. 68, Issue 9), in which he affirms that there is no relationship between the dusty environments that cause silicosis and morbidity. In 1951, with the cooperation of a mining operation (S mining operations) believed to be the Sado mines, Tanno acknowledged that dust inhalation was worst among laborers engaged in drilling, transportation, and pillaring.



Table 1: The number of years required for the onset of silicosis according to Ken Saito’s “Research Findings and Addendum on Silicosis” (Hokuetsu Medical Journal, Vol. 59, Issue 6, 1944) (table created by Nagatani based on the paper).


Table 2 Kiyonobu Tanno, “Morbidity by Pit Mining Occupation and Years of Attendance”, published in “Silicosis Incidence Rate and Progression by Occupation and Years of Service” (Niigata Medical Journal Vol. 68, Issue


However, he argues that even in an environment with a lot of dust, the prevalence of silicosis increases in proportion to the length of time spent working in the pits. Based on Table 2, it is apparent that even among drillers who had worked for less than five years, the probability of contracting stage II silicosis-which is believed to be severe-was 7.9%.

Thus the fact that many Koreans were assigned to rock drilling, transportation, and pillaring is not proof of racial discrimination and subsequently cannot be declared forced labor.


  1. The State of Korean Workers as Reflected in Primary Sources

The claim that the wages Koreans received after deductions were derisory was countered earlier in the first presentation by Nishioka’s report. The Japan Mining Industry’s “Survey Report on Korean Laborers” presented in this report states that the average wage in July 1940 was \66.77 JPY. Considering that this rose to over \80 JPY, as recorded in the document “Concerning Korean Personnel Management” produced three years later, the wages Koreans received were quite sufficient. This can also be inferred from the case of a runaway described in the Special Higher Police Monthly Report.

In November 1942, four Koreans dissatisfied with wages and food provisions paid their colleagues \130 JPY to assist them in leaving the mines. This would mean that each person had more than \30 JPY in cash in their possession, and considering the costs of transportation and food that the journey after their flight would entail, it is likely that they had even more.

Also, in February 1943, spurred by the same motivation, four female Korean workers paid \75 JPY for help in deserting the mines. Koreans were not fleeing appalling circumstances in fear of their lives but simply leaving to seek out better-paid jobs with better conditions.

Regarding the point that compulsory contract renewals prevented workers from returning home, notices of transfer issued in accordance with workers’ desire to return to the peninsula following the expiration of their contracts were obtained from the Korean cigarette distribution list (5).

Compiled on April 22, 1945, the Historical Awareness Research Committee acquired this historical document in which the names of 11 Koreans who returned home upon the expiration of their contracts are recorded. It is worth noting that since such a large number of laborers were repatriated just before the end of the war, it is quite possible that other Koreans had returned home prior to this.

Furthermore, the notice of transfer states that all returnees were provided with a ten-day supply of cigarettes. Is it really appropriate to describe these Koreans, who were generously provided with cigarettes-a valuable commodity at the time-as slave laborers? In “Concerning Korean Personnel Management”, it is clearly stipulated that the financial incentives awarded for contract renewal had a substantial effect on the continued motivation of workers.

This is how a thorough reading of the primary sources reveals that the Sado mines were not the site of forced labor.


Photo: Notification of transfer for 11 Korean workers from Soai Dormitory 3 obtained by the Historical Awareness Research Committee. This was issued due to the expiration of their contracts and subsequent wish to return home.


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