Abstract: A connector includes first and second connector housings which are fitted together. A seesaw or lever-type lock piece is provided in one of said connector housings and a hooking part is provided on the other connector housing for being hooked by a first downward projection of the lock piece. A detecting member is mounted for free sliding movement along the upper face of the lock piece. After a fitting operation of both housings is carried out, the detecting member is pushed forwardly. When the connector housings are in an incomplete fitted position or state, since the first downward projection is mounted on the hooking part and the lock piece is in an oblique position, the pushing of the detecting member is prevented and an incomplete fitted state is detected. When the detecting member is further pushed in, one of the housings is pushed in with the lock piece and is properly fitted.