A connector includes a housing having a connecting portion, an insertion portion, and slits, and a retainer having arms, and engaging portions. The engaging portions are engaged with a flange portion of a first pipe member so as to retain the first pipe member. An inclinatory contact portion is provided between inner circumferential surfaces of the slits and outer surfaces of the, such that the pair of arms are urged in directions of approaching each other when a force to pull out the first pipe member from the insertion portion is exerted.