A lever (24) is formed with a separating cam surface (30) and an escaping space (31) disposed in a region more distant from a rotary shaft (13) than the separating cam surface (30). The separating cam surface (30) presses cam projections (23) of a moving plate (18) in a direction away from the rotary shaft (13) to separate both housings (10, 40) in the process of rotating the lever (24) to an initial position with the both housings (10, 40) connected. The cam projections (23) are accommodated into the escaping space (31) while being separated from the separating cam surface (30) in the process of rotating the lever (24) from the initial position to a connection position with the both housings (10, 40) separated and the moving plate (18) located at a protection position.