A diaphragm pump is provided. The diaphragm includes an upper housing, a diaphragm, and a lower housing. Recessed parts are formed in the surfaces of the upper and lower housings that face the diaphragm to define an upper pump chamber and a lower pump chamber above and below the diaphragm. A suction port and a discharge port are formed in the lower housing to communicate with the lower pump chamber. Branch channels are formed in the lower housing and the upper housing to communicate the suction port and the discharge port with the upper pump chamber. Suction-side check valves are respectively provided between the suction port and the upper pump chamber and between the suction port and the lower pump chamber. Discharge-side check valves are provided between the discharge port and the upper pump chamber and between the discharge port and the lower pump chamber.