A female housing (10) includes cam pins (14). A lever (70) is mounted on a male housing (30), and arms (73) of the lever (70) are formed with bearing portions (74) and cam grooves (71) engageable with the cam pins (14). An engaging groove (78) is formed adjacent to the cam groove (71) in each arm (73), and an engaging pin (17) is provided adjacent to each cam pin (14) on the female housing (10). The engaging grooves (78) can receive the engaging pins (17) during the rotation of the lever (70) and have inclination restricting surfaces (79) for restricting the inclination of the female housing (10) by sliding in contact with the engaging pins (17) as the lever (70) is rotated if the posture of the female housing (10) being connected is inclined relative to the female housing (30).