A pedal boss, to which an accelerator pedal is fixed, has a projection-receiving space, which circumferentially extends on a circumferential side of a closing-side end wall in an accelerator-opening direction and receives a projection. When the pedal boss is rotated in an accelerator-closing direction, the pedal boss is rotatable to an accelerator-full-closing position of the pedal boss without being stopped by the projection through engagement with the projection regardless of a rotational position of the projection.