Ihara (written: 井原 or 伊原) is a Japanese surname. Notable people with the surname include:

• Haruki Ihara (伊原 春樹, born 1949), Japanese baseball player and manager
• Isamu Ihara (井原 勇, 1926–2007), Japanese politician
• Junichi Ihara (伊原 純一, born 1956), Japanese diplomat
• Katsuhiko Ihara (井原 勝彦, born 1943), Japanese rower
• Keiko Ihara (井原 慶子, born 1973), Japanese racing driver
• Les Ihara Jr. (born 1951), American politician
• Masami Ihara (井原 正巳, born 1967), Japanese footballer
• Michio Ihara (born 1928), Japanese sculptor
• Mitsugu Ihara (庵原 貢, 1903–1979), Japanese naval officer
• Ihara Saikaku (井原 西鶴, 1642–1693), Japanese poet and writer
• Shintaro Ihara (井原 伸太郎, born 1991), Japanese footballer
• Takatada Ihara (井原 高忠, 1929–2014), Japanese television director and producer
• Tsuyoshi Ihara (伊原 剛志, born 1963), Japanese actor
• Yasuhide Ihara (井原 康秀, born 1973) Japanese footballer
• Yasutaka Ihara (伊原 康隆, born 1938), Japanese mathematician

See also

• Ihara District, Shizuoka, a former district of Shizuoka Prefecture, Japan
• Ihara zeta function
• Ihara's lemma