A pump device (1) includes a piezoelectric pump (10) and an outer casing (70). The piezoelectric pump (10) includes a pump casing having inlets (400) and an outlet (520), a vibration plate (31) disposed inside the pump casing and dividing an internal space (500) of the pump casing into a first space (501) on a side near the inlets (400) and a second space (502) on a side near the outlet, and a piezoelectric element (20) disposed on the vibration plate (31). The outer casing (70) forms a flow path composed of an internal space (700) that allows communication between an external inlet (701), which communicates with the outside, and the inlets (400). The flow path has a part that is parallel to an outer main surface (40op) of the pump casing in which the inlets (400) are formed, the part being located outside the outer main surface (40op).