PURPOSE: To dispense with a mechanical check valve by providing piezoelectric members with independent piezoelectric plates on the feed port side and the discharge port side respectively on a plate-shaped member with a fluid path formed with the feed port and the discharge port at both ends to form one face of the fluid path.

CONSTITUTION: A protruded section 19 to fix the center section of a piezoelectric member is formed at the center of a plate-shaped supporter frame 8 formed with a feed port 3 and a discharge port 4 at both ends, a linear fluid path 22 to communicate the feed port 3 and the discharge port 4 is formed. Electrodes 11a and 11b are stuck at both ends on a support plate 9 overlappingly stuck with the supporter frame 8, a piezoelectric plate 10 with conducting terminals 12a-12c are stuck at the center to constitute the piezoelectric member. A bellows type coupler 23 formed with multiple grooves on the front and rear faces of the support plate 9 is provided in the peripheral region of a piezoelectric plate 10 on the support plate 9, thereby the curved deformation of the piezoelectric member due to the excitation to the electrodes 11a and 11b is allowed, the pump function can be exerted.