A connector which is detachably connected to a cylindrical section is prevented from unintentionally disconnecting and breaking. The connector has inner and outer cylinder members. The inner cylinder member has an engagement plate protruding from the inner peripheral surface of an inner cylinder body and engaging with a recess formed in the outer peripheral surface of the cylindrical section, and also has slits arranged radially and extending from the engagement plate to a part of the inner cylinder body. The engagement between the recess and the engagement plate restricts the axial movement of the inner cylinder member relative to the cylindrical section. When the outer cylinder member is mounted on the inner cylinder member, the inner peripheral surface of the outer cylinder member is in contact with the outer peripheral surface of the inner cylinder member, and the displacement of the engagement plate in the diameter expansion direction is restricted.
