A pump (1) includes a vibrating plate (15) that has a central part (21), a frame part (22), and connecting parts (23 to 26), a piezoelectric element (16) that is stacked over the central part (21) and configured to cause flexural vibrations to occur concentrically from the central part (21) to the connecting parts (23 to 26), and an opposed plate (13) that is stacked over the frame part (22) and positioned facing each of the connecting parts (23 to 26) with a spacing therebetween. The vibrating plate (15) has such a resonant mode that an antinode occurs in each of the central part (21) and the connecting parts (23 to 26). The opposed plate (13) has, at positions facing the connecting parts (23 to 26), a plurality of channel holes (39 to 43) through which a fluid flows.