Jōban Coalfield

The Jōban Coalfield (常磐炭田) was one of the most significant coal-producing regions in Honshu, extending approximately 90 kilometers along the Pacific coast from Tomioka Town in Fukushima Prefecture's Futaba District southward to Hitachi City in Ibaraki Prefecture. Coal was first discovered in the area in 1855 (Ansei 2; some accounts give 1856) by Katayose Heizō (片寄平蔵), a timber merchant who found an outcrop at Miroku-zawa in Shiramizu Village (present-day Uchigō district of Iwaki City), only a few years after Commodore Perry's arrival in Japan.

The coalfield developed rapidly from the 1870s onward, particularly after the 1877 Satsuma Rebellion disrupted coal supplies from the Chikuhō region in Kyushu, drawing attention to the coalfield's strategic proximity to Tokyo. The Jōban Railway Line (now part of JR East) was established in 1897 primarily to transport coal from the mines. At its peak, the Jōban Coalfield encompassed over 130 individual mines, and output reached a record of about 4.3 million tons in 1957, making it Japan's third-largest coalfield after Ishikari and Chikuhō. The coal was notably low-grade and highly sulfurous, and extraction required advanced drilling technology due to severe geological folding. Mining operations also had to contend with massive underground water infiltration, requiring approximately 4 tons of groundwater to be pumped out for every 1 ton of coal extracted.

During World War II, the Japanese government implemented a Coal Mine Rationalization Plan in 1943, forcing the merger of the Iwaki Coal Mine (磐城炭鉱, operated by the Asano zaibatsu) and the Iriyama Coal Mining Company (入山採炭, operated by the Ōkura zaibatsu) in 1944 to form the Jōban Coal Mining Company (常磐炭鉱株式会社). The mines became a critical component of the wartime coal production increase campaign (増産運動), as Japan desperately needed domestic fuel sources with overseas supply lines under increasing Allied interdiction. Thousands of Korean civilians were forcibly conscripted and brought to the Jōban mines to meet escalating production targets, enduring dangerous working conditions, long hours, and inadequate provisions.

After Japan's surrender, Emperor Shōwa made a notable visit to the coalfield in August 1947, personally inspecting the Yumoto No. 6 shaft — marking the first time a Japanese emperor descended into a mine. The coalfield continued operations through the postwar period but faced terminal decline beginning in the 1960s as Japan shifted from coal to petroleum. The final closure of the Jōban Coal Mine's western operations came in 1976, ending 120 years of mining history. The Jōban Kōsan company, successor to the wartime mining firm, pivoted to tourism and in 1966 opened the Jōban Hawaiian Center (now Spa Resort Hawaiians) utilizing the hot spring water that had once plagued mining operations.

Today, the Iwaki City Coal and Fossil Museum (いわき市石炭・化石館 ほるる) preserves the history of the coalfield, and scattered industrial heritage sites — including former mine shafts, railway remnants, and the coal washing facility ruins — can be found throughout the Iwaki and Kitaibaraki areas. The forced labor history, including the experiences of Korean conscripted workers, remains an important but often underrepresented aspect of the coalfield's wartime legacy.