A lift amount of a valve plug is controlled with respect to a period of time from valve-closing operation instruction time for an electric opening/closing valve to arrival at a preset quick valve-closing operation position at which a flow line of a fluid discharged from a discharge port of a nozzle is in a constricted state, in accordance with a driving action of an electric actuator. The valve plug of the electric opening/closing valve is controlled to be at a closed position after the arrival at the quick valve-closing operation position. Accordingly, it is possible to prevent the incontinent liquid drip from the nozzle during the valve-closing operation of the electric opening/closing valve.