A control device for a vehicular on/off control valve having current control means 386 is provided. The current control means 386 is operative to allow a solenoid current IRL to be set in an operation initiating current value IRN, needed for initially switching the on/off control valve from the turn-off state to the turn-on state during a current-supplied state of a switching electromagnetic solenoid 102. It is operative to allow a sustaining current value IHD lower than the operation initiating current value IRN after the turn-on state is attained. Thus, solenoid current IRL is reduced without impairing an operation of a switching electromagnetic solenoid valve 104. Therefore, waste current can be reduced to be lower than that achieved with the conventional on/off control as shown in FIG. 8, thereby minimizing power consumption of the switching electromagnetic solenoid valve 104.