Ministry of Railways (Tetsudōshō)

The Ministry of Railways (鉄道省) was established on May 15, 1920 as the successor to the Railway Board (鉄道院), with Motoda Hajime as the first minister. Organised at first into six bureaus — supervision, traffic, construction, engineering, workshops and accounts — it directly operated Japan's government railway network (the "ministry lines") while supervising private railways and tramways and handling related road transport and tourism. The trunk network created by nationalisation in 1906 was extended into the regions under the ministry.

Between the wars the ministry completed projects that reshaped Japan's transport geography. The Tanna Tunnel on the Tōkaidō Main Line opened in 1934 after sixteen years of construction, sharply cutting journey times between Tokyo and Kansai. The Kanmon railway tunnel linking Honshu and Kyushu opened in 1942, one of the world's earliest undersea railway tunnels; it allowed Kyushu coal to move to Honshu's industrial zones without shipping, which mattered greatly as wartime tonnage ran short.

After war broke out with China, traffic towards Korea, Manchuria and the continent surged and the Tōkaidō and San'yō lines neared capacity. The ministry therefore planned major infrastructure projects, including the ambitious Bullet Train Plan (弾丸列車計画) for a new standard-gauge Tokyo–Shimonoseki high-speed line, with the idea of an eventual undersea link to Korea. The Diet approved its budget in 1940; land was purchased and work began on the Shin-Tanna and Nihonzaka tunnels, but construction was halted later in the war. The land and partly completed tunnels were reused for the Tōkaidō Shinkansen, opened in 1964.

In November 1943, the ministry was reorganized into the Ministry of Transport and Communications (運輸通信省) as part of wartime government consolidation, merging with the Ministry of Communications; this became the Ministry of Transport in May 1945. Japanese sources note that despite heavy air raids the railways largely kept running until August 15, 1945. After the war, in line with GHQ policy, the national railways were separated from the government and reorganized as the public corporation Japanese National Railways (日本国有鉄道, JNR) on June 1, 1949, which was divided and privatised as the JR companies in 1987.