A connector includes a first housing including a receptacle, a second housing capable of being engaged with or disengaged from the receptacle, a locked portion provided in the first housing, a locking portion provided in the second housing capable of locking an engaged state of the first housing and the second housing by locking the locked portion, and a rib provided in one of the first housing and the second housing, which includes an inclined surface and a flat portion in sequence along the connecting direction of the first housing and the second housing. A position and a length of the rib and a position of the locking portion are set in such a manner that the first housing and the second housing start to be engaged in the order of the inclined surface of the rib, the locking portion, and the flat portion of the rib.