A connector includes a connector housing having a lock portion configured to lock a mated housing; a guide groove formed in the connector housing and guiding a fitting detection member from a temporary locking position to a final locking position; an arm portion having an engagement protrusion provided on an extended free end extending in a direction of approaching the lock portion from the fitting detection member and abutting against the lock portion at the temporary locking position; and a backlash filling protrusion that is formed on a protruding plate portion, to be engaged with the guide groove, of the fitting detection member, and is configured to tilt the fitting detection member in a direction in which a locking amount of the engagement protrusion with respect to the lock portion is increased at the temporary locking position.