A lever (30) is supported on a first housing (10) for rotation between an initial position and a connection position. A resiliently deflectable holding arm (35) is formed on a main body (31) of the lever (30) and is configured to be locked to the first housing (10) for holding the lever (30) at the initial position so that the lever (30) does not rotate toward the connection position (connecting direction B). The holding arm (35) is formed with a regulating projection (38). The main body (31) is formed with a stopper (39) configured to regulate a displacement in a hold releasing direction A of separating the holding arm (35) from the first housing (10) by locking the regulating projection (38) when the main body portion (31) is displaced in the connecting direction B with the holding arm (35) locked to the first housing (10).