Yōichirō, Yoichiro or Youichirou (written: 洋一郎, 陽一郎, 與一郎 or 曜一朗) is a masculine Japanese given name. Notable people with the name include:
Yoichiro Esaki (江崎 洋一郎) (born 1958), Japanese politician
Yoichirō Hirase (平瀬 與一郎) (1859–1925), Japanese malacologist
Yoichiro Kakitani (柿谷 曜一朗) (born 1990), Japanese footballer
Yoichiro Kawaguchi (河口 洋一郎) (born 1952), Japanese artist
Yōichirō Morikawa (森川 陽一郎) (born 1979), Japanese film director, screenwriter and actor
Yoichiro Murakami (村上 陽一郎) (born 1936), Japanese philosopher
Yoichiro Nambu (南部 陽一郎) (born 1928), Japanese-born American physicist
Yōichirō Takahashi (高橋 陽一郎) (born 1963), Japanese film and television director
