Former Navy Ministry

The Ministry of the Navy (海軍省, Kaigun-shō) was established in 1872 (Meiji 5) when the Hyōbushō (Department of Military Affairs) was split into separate Army and Navy ministries. It served as the cabinet-level organ responsible for the administrative affairs of the Imperial Japanese Navy (IJN), including personnel, budgets, shipbuilding programs, and policy coordination with the civilian government.

In December 1894 (Meiji 27), the Navy Ministry relocated to a newly completed red-brick building in Kasumigaseki, Kojimachi-ku (present-day Chiyoda Ward), designed by the distinguished British architect Josiah Conder. The imposing Western-style building, nicknamed "Aka-Renga" (赤レンガ, Red Brick), became the enduring symbol of Japan's naval administration. The Naval General Staff (軍令部, Gunreibu), responsible for operational planning and fleet command, was housed in an adjacent building on the same compound, creating the dual administrative-operational nexus of the Imperial Japanese Navy.

During the Pacific War (1941–1945), the Navy Ministry building served as the administrative headquarters from which the IJN's vast wartime operations were coordinated. Key decisions regarding naval strategy, fleet mobilization, aircraft production, and the allocation of dwindling resources were made within its walls. The Navy Minister (海軍大臣) who occupied this building held one of the most powerful positions in the wartime cabinet, with the authority to make or break governments through the military minister appointment system (軍部大臣現役武官制). Notable wartime Navy Ministers who served here included Shimada Shigetarō and Yonai Mitsumasa.

The ministry's role was complementary to that of the Army Ministry (陸軍省) at Ichigaya. While the Army Ministry managed the Imperial Japanese Army, the Navy Ministry controlled all naval affairs. The interservice rivalry between these two ministries profoundly shaped Japan's wartime decision-making, from the decision to advance into Southeast Asia to debates over war termination.

Following Japan's surrender on August 15, 1945, the Navy Ministry was formally abolished on November 30, 1945, together with the Imperial Japanese Navy itself, under orders from the Allied occupation authorities. The dissolution was part of the comprehensive demilitarization of Japan mandated by the Supreme Commander for the Allied Powers (SCAP).

After the war, parts of the former Navy Ministry building were temporarily used by the Ministry of Health and Welfare (厚生省). The red-brick structure gradually deteriorated and was demolished in stages, with final removal completed by 1985 (Showa 60). In 1954, Central Government Building No. 1 (中央合同庁舎第1号館) was constructed on the site as Japan's first postwar purpose-built central government office complex. Today it houses the Ministry of Agriculture, Forestry and Fisheries (農林水産省, MAFF), the Forestry Agency, and the Fisheries Agency.

A stone monument (海軍省跡・軍令部跡の碑) commemorating the former Navy Ministry and Naval General Staff stands at the northeast corner of the nearby Central Government Building No. 5 (中央合同庁舎第5号館). The monument's central inscription reads "軍令部" (Naval General Staff), with "海軍省" (Navy Ministry) inscribed on the right side. The calligraphy was executed by former Prime Minister Nakasone Yasuhiro. Access to view the monument requires visitor identification at the building entrance.