- Titles: Chikugo no kami
- Other Names: 古賀増 (Koga Masaru)
- Japanese: 古賀 謹一郎 (Koga Kin'ichirô)
Koga Kin'ichirô was a Confucian scholar in service to the Tokugawa shogunate. He is known for his translation work and involvement otherwise in activities related to the shogunate's engagement with Western powers in the 1850s, including being one of the signers of the 1854 Treaty of Shimoda (along with Tsutsui Masanori and Kawaji Toshiakira).
His students included Hirata Tôsuke.
- Ishin Shiryô Kôyô 維新史料綱要, vols 1, 2 (1937).
- Mitani Hiroshi, David Noble (trans.), Escape from Impasse, International House of Japan (2006), 247-250, 292.