A connector includes a connector housing and a fitting assurance member. A repulsion arm of the connector housing is sandwiched between an arm contact portion of a mating connector and an arm displacement regulation portion of the fitting assurance member and the repulsion arm is elastically deformed to be pressed to an outside by a leading end portion of the arm contact portion to be stretched in a straight line, when the leading end portion of the arm contact portion slides on an inner inclined surface of an arm inclined portion of the repulsion arm toward an arm leading end of the repulsion arm.