A diaphragm pump comprising: a diaphragm including a pump portion; a pump housing configured to store the diaphragm and form a pump chamber together with the pump portion; a suction passage through which a fluid flows to the pump chamber when the pump chamber expands; a discharge passage through which a fluid discharged from the pump chamber flows when the pump chamber contracts; a suction valve arranged in the suction passage and configured to open and close the suction passage; and a discharge valve arranged in the discharge passage and configured to open and close the discharge passage, wherein at least one valve of the suction valve and the discharge valve is made of an elastic material, and includes a shaft including a first end portion and a second end portion, and a plate-shaped valve element extending from the first end portion of the shaft in a direction orthogonal to an axis of the shaft, the pump housing includes: a first housing member including a shaft hole formed from a blind hole in which the second end portion of the shaft is inserted, and a seat surface to which one of part of the suction passage and part of the discharge passage opens; and a second housing member configured to press the first end portion of the shaft inserted into the shaft hole toward the second end portion and hold the shaft together with the first housing member, the first end portion of the shaft includes a projection (82, 91) projecting toward the second housing member, the valve element is formed to come into tight contact with the seat surface when the shaft is sandwiched between the first housing member and the second housing member, and the second housing member includes a columnar body facing the shaft, characterized in that a total length of the shaft including the projection is slightly longer than an interval between a bottom of the shaft hole and a distal end of the columnar body in a completed state of the diaphragm pump. a diaphragm including a pump portion; a pump housing configured to store the diaphragm and form a pump chamber together with the pump portion; a suction passage through which a fluid flows to the pump chamber when the pump chamber expands; a discharge passage through which a fluid discharged from the pump chamber flows when the pump chamber contracts; a suction valve arranged in the suction passage and configured to open and close the suction passage; and a discharge valve arranged in the discharge passage and configured to open and close the discharge passage, wherein at least one valve of the suction valve and the discharge valve is made of an elastic material, and includes a shaft including a first end portion and a second end portion, and a plate-shaped valve element extending from the first end portion of the shaft in a direction orthogonal to an axis of the shaft, the pump housing includes: a first housing member including a shaft hole formed from a blind hole in which the second end portion of the shaft is inserted, and a seat surface to which one of part of the suction passage and part of the discharge passage opens; and a second housing member configured to press the first end portion of the shaft inserted into the shaft hole toward the second end portion and hold the shaft together with the first housing member, the first end portion of the shaft includes a projection (82, 91) projecting toward the second housing member, the valve element is formed to come into tight contact with the seat surface when the shaft is sandwiched between the first housing member and the second housing member, and the second housing member includes a columnar body facing the shaft, characterized in that a total length of the shaft including the projection is slightly longer than an interval between a bottom of the shaft hole and a distal end of the columnar body in a completed state of the diaphragm pump. a first housing member including a shaft hole formed from a blind hole in which the second end portion of the shaft is inserted, and a seat surface to which one of part of the suction passage and part of the discharge passage opens; and a second housing member configured to press the first end portion of the shaft inserted into the shaft hole toward the second end portion and hold the shaft together with the first housing member, the first end portion of the shaft includes a projection (82, 91) projecting toward the second housing member, the valve element is formed to come into tight contact with the seat surface when the shaft is sandwiched between the first housing member and the second housing member, and the second housing member includes a columnar body facing the shaft, characterized in that a total length of the shaft including the projection is slightly longer than an interval between a bottom of the shaft hole and a distal end of the columnar body in a completed state of the diaphragm pump.