PURPOSE: To permit a single valve to perform capacity control in multiple steps by putting bypass holes in communication with a pair of fluid pockets through coupling lines.

CONSTITUTION: Bypass holes 20, 24 are put in communication with a pair of fluid pockets 13 through coupling lines. Each of these coupling lines is composed of a groove 25 formed at one side of No.1 plate 5 and leading to respective bypass hole 20, 24, a bottom plate 26 placed on one side of the No.1 plate 5 and enclosing the groove 25, and a through hole bored in this bottom plate 26 and tying the fluid pockets 13 to the groove 25. This through hole 28 is put in communication with the fluid pockets 13 and groove 25. This permits one valve to perform capacity control.