A lock member has: a contact part that contacts one surface of an object to be connected; a locking part that has a shape allowing engagement with a part to be locked formed on the object to be connected; a connection part; and a pressure-receiving part that is pressed by a pressing member. The lock member includes at least one contact provided with a fixing function and used to enable electrification. The locking part projects in a direction that moves away from a board-mounting surface at a side near the board-mounting surface, at a position corresponding to the part to be locked of the object to be connected. The contact part is positioned on the side far from the board-mounting surface at the side facing the locking part, and at a position closer to an insertion side of the object to be connected than the locking part.