A connector (2) which is detachably connected to a cylindrical section (5) is prevented from being unintentionally disconnected and from breaking. The connector (2) has an inner cylinder member (10) and an outer cylinder member (40). The inner cylinder member (10) has an engagement plate (30) protruding from the inner peripheral surface of an inner cylinder body (20) and engaging with a recess (7) formed in the outer peripheral surface of the cylindrical section (5), and also has slits (11) arranged radially and extending from the engagement plate (30) to a part of the inner cylinder body (20). The engagement between the recess (7) and the engagement plate (30) restricts the axial movement of the inner cylinder member (10) relative to the cylindrical section (5). In a state in which the outer cylinder member (40) is mounted on the inner cylinder member (10), the inner peripheral surface of the outer cylinder member is in contact with the outer peripheral surface of the inner cylinder member, and thus the displacement of the engagement plate (30) in the diameter expansion direction is restricted.
