Between a housing and a position ensuring member, provided are: a first locking mechanism that locks move of the position ensuring member at a standby position in an ensuring-operation direction toward a fitting assured position when a lever member is not at a completely fitted position; and a second locking mechanism that locks move of the position ensuring member at the fitting ensured position in an ensuring-release direction that is a reverse direction of the ensuring-operation direction when the lever member is at the completely fitted position. Between the lever member and the position ensuring member, provided is a locking release mechanism that releases a locked state of the position ensuring member with the first locking mechanism when the lever member comes at the completely fitted position.