Fujii Kōichi (藤井 較一, 24 September 1858 – 9 July 1926) was an admiral in the early Imperial Japanese Navy.

[1] At the start of the First Sino-Japanese War, Fujii was serving with the Imperial Japanese Navy General Staff; however, he was assigned to combat duty on the captured Chinese gunboat Soko, the gunboat Ōshima and the corvette Musashi[2] on which he was promoted to lieutenant commander and appointed executive officer from February 1895.

After the war, Fujii was sent to the United Kingdom to supervise the construction of the cruiser Takasago, and was promoted to commander on 1 December 1897.

He participated in combat missions during the first year of the Russo-Japanese War, including the pursuit of the Russian Vladivostok Cruiser Squadron during the Hitachi Maru Incident and the Battle off Ulsan.

He was promoted to vice admiral on 1 December 1909 and became Vice-Chief of the Imperial Japanese Navy General Staff.