Kōichirō or Koichiro (written: 晃一郎, 光一郎, 弘一郎, 鴻一郎, 紘一郎, 浩一郎, 耕一郎, 航一郎, 倖一郎 or 小一郎) is a masculine Japanese given name. Notable people with the name include:
Kōichirō Genba (玄葉 光一郎) (born 1964), Japanese politician
Koichiro Harada, Japanese mathematician
Koichiro Hirayama (平山 紘一郎) (born 1946), Japanese sport wrestler
Kōichirō Hoshino (星野 倖一郎), Japanese manga artist
Koichiro Ichimura (市村 浩一郎) (born 1964), Japanese politician
Koichiro Katafuchi (片渕 浩一郎) (born 1975), Japanese footballer
Kawada Koichiro (川田 小一郎) (1836–1896), Japanese businessman and banker
Koichiro Kawano (born 1981), Japanese golfer
Kōichirō Matsuura (松浦 晃一郎) (born 1937), Japanese diplomat
Koichiro Mitani (三谷 浩一郎) (born 1968), Japanese judoka
Kōichirō Morioka (森岡 紘一朗) (born 1985), Japanese racewalker
Koichiro Nagatomo (長友 耕一郎) (born 1982), Japanese footballer
Koichiro Shimizu (清水 鴻一郎) (born 1946), Japanese surgeon and politician
Kōichirō Tomita (冨田 弘一郎) (1925–2006), Japanese astromer
Kōichirō Uno (宇能 鴻一郎) (born 1934), Japanese writer
Kōichirō Yasunaga (安永 航一郎,) (born 1962), Japanese manga artist
