Locking projections (31) formed on resiliently deformable resilient arms (30) hold a lever (20) at an initial position by engaging locking recesses (18). Resilient escaping portions (19), on which the locking projections (31) slide in the process of rotating the lever (20) between an assembled position and the initial position, are resiliently deformable in directions away from the locking projections (31). Upon rotating the lever (20) from the assembled position to the initial position after the lever (20) is assembled with a first housing (10), both the resilient arms (30) and the resilient escaping portions (19) are resiliently deformed. Thus, as compared with the case where only the resilient arms (30) are resiliently deformed, degrees of resilient deformation of the resilient arms (30) are reduced, wherefore deformations of the locking projections (31) to be crushed can be suppressed.