A connector assembly includes a female housing (11) and a male housing (12) connectable to each other. A lever (16) is supported rotatably on shafts (43) of the male housing (12). The male housing (12) includes walls (55) outside side surfaces. The lever (16) includes two plates (74) projecting from a lever operating portion (73) while facing each other and wall engaging portions (93) provided on the respective plates (74). The wall engaging portions (93) are configured to enter entrance spaces (66) inward of the walls (55) with the plates (74) facing the side surfaces of the male housing (12) and the shafts (43) being fit into bearings (81) of the lever (16) and contacting the walls (55) from outside by the plates (74) respectively erroneously facing the side surfaces of the male housing (12) not corresponding thereto.