A connector includes a housing to be attached to a front face of a panel. A panel has a mounting opening through which a rear portion of the housing is inserted. The rear portion of the housing has a lance extending in a direction parallel to the front face of the panel. The mounting opening has a concave portion through which the lance is inserted. When the housing is moved in a first direction along the front face of the panel, a locking piece that continues to a concave portion locks the tip of the lance such that the housing is difficult to move in a second direction.