A piezoelectric pump is provided with an actuator containing a piezoelectric element and a vibrating sheet； a first diaphragm, positioned opposite the actuator, with a first connecting hole provided therein； a pump chamber formed by the space between the actuator and the first diaphragm； and a second diaphragm positioned opposite the first diaphragm. The part of the second diaphragm opposite the first connecting hole is provided with an opposing wall portion that prevents a fluid that has been introduced into the pump chamber via the first connecting hole from flowing back towards a suction side via the first connecting hole.
