Komatsushima, city, eastern Tokushima ken (prefecture), eastern Shikoku, Japan. It lies on Komatsushima Bay on the east coast of Shikoku and adjoins Tokushima to the north and west.
Komatsushima was originally a small fishing village and a temple town of Ninna Temple in Kyōto. It developed as a commercial centre after the establishment of port facilities in 1899. Regular ferry service began operation there in 1913, connecting Shikoku island with major cities on Honshu, including Wakayama and the municipalities of the Ōsaka-Kōbe metropolitan area. A large spinning mill opened in Komatsushima in 1923. It was designated a city in 1951 and is a popular holiday resort. Pop. (2010) 40,614; (2015) 38,755.