PURPOSE: To prevent energy loss without provision of any separate valve where a function of check valve is not required by installing a solenoid actuator inside a check valve, and fixing a movable valve element of the check valve to the opened condition through the action of the actuator.

CONSTITUTION: The coil 8 of a solenoid actuator 7 is energized so that the armature 9 is moved in the direction of arrow in the attached illustration, and a movable valve element 4 is heaved by a rod 10 against the action of a preloading spring 3. The takeout holes 11, 12 of the coil 8 are stopped with an insulating substance sustaining the pressure of the fluid. In case a function of check valve is not required, the valve element 4 is heaved forcedly against the action of the spring 3 by energizing the actuator 7, and the section area of the flow path determined by the gap between the valve seat 2 and valve element 4 is opened large, which allows reduction of the loss when the fluid flows.