In order to prevent shaft portion from being broken in ejection of base portion from mold, method for manufacturing interdental cleaning tool includes: base portion forming step of forming base portion by filling first space of primary mold (50) with synthetic resin, which includes first and second mold members (50A, 50B)； and cleaning portion forming step of forming cleaning portion around shaft portion by filling second space of secondary mold with elastomer. Base portion forming step uses first and second mold members (50A, 50B). First and second molds include: first and second contact surfaces (51A, 51B)； pair of first and second spaced-apart portions (54A, 54B)； and first and second connection portions (52A, 52B), angle (0) between each of first and second spaced-apart portions (54A, 54B) and separation plane being acute.
