It is aimed to provide a connector capable of preventing the breakage of side walls (18). A housing (10) includes a mounting hole (17) into which a retainer (60) is mounted, and side walls (18) for closing the mounting hole (17) from opposite sides. The side wall (18) is provided with lock receiving portions (22). Lock protrusions (68) configured to slide while deflecting the side walls (18) in the process of inserting the retainer (60) into the mounting hole (17) and release the side walls (18) from a deflected state and enter the lock receiving portions (22) when reaching positions corresponding to the lock receiving portions (22) are provided on outer surfaces of the retainer (60). Both end corner parts of the lock protrusion (68) in a sliding width direction (Y) perpendicular to a sliding direction on the side wall (18) are chamfered.