To simplify and make compact the structure of a shut-off valve by constituting at least two shut-off valve closing bodies of one common valve diaphragm, and to accurately generate valve opening/closing pressure by increase the sureness of a function.

Pressing springs for giving support action to a valve closing body are provided in shut-off valves 4 and 5, and the valve opening and closing pressures of the shut-off valves 4 and 5 are properly matched with each other by clamping forces additionally generated by the pressing springs. Only the discharge shut-off valve 5 is provided with a pressing spring 63, and the pressing valve 63 is housed between the bottom surface 36 of a valve diaphragm 40 and a lower port 31 in an inner room 38. Since the pressing spring 63 is, for example, engaged with the valve diaphragm 40 in a side opposite an annular bead 54 and the clamping operation of the annular bead 54 is increased by a spring force, the valve opening pressure of the shut-off valve 5 is increased.