An in-vehicle device wirelessly sends a request signal to an assistance-possible area in which a user of a welfare-use seat device can be assisted. When a wireless portable key device, i.e., a remote control is present inside of the assistance-possible area, the portable key device returns a response signal containing an ID code. When receiving the response signal, the in-vehicle device executes a collation relative to the ID code contained in the response signal. When the collation is successfully completed, a short-depression movement mode is designated. When a short-time manipulation or depression is once applied to an operation instruction switch of the wireless portable key device under the short-depression movement mode being designated, the movement of a welfare-use seat device is started toward a movement end position without need further continued manipulation or depression to the operation instruction switch.
