A diaphragm pump (1, 101) including: a housing (2, 102); a piston (3, 103) which is placed in the housing to be coaxial with the housing, and which is disposed to be reciprocally movable in an axial direction of the housing; a shaft (4, 104) which is configured to be moved in conjunction with the piston in a state where one axial end side is in contact with the piston; a rolling diaphragm (5,105) having: a lid portion (35, 135) which is placed on the one axial end side of the piston; an open-end portion (36, 136) which is attached to the housing; and a folded portion (37, 137) which is placed between the lid portion and the open-end portion, the lid portion being reciprocally movable integrally with the piston with respect to the open-end portion which is positionally fixed by the housing; a pump chamber (51, 151) which is defined by the rolling diaphragm on a one axial end side of an interior of the housing with respect to the rolling diaphragm, a volume of an interior of the chamber being variable; a driving device (6, 106) having: a motor section (30, 130); and an output axle (31, 131) which is placed coaxially with the shaft, and which is coupled to another axial end side of the shaft, the driving device being attached to another axial end side of the housing, the driving device being able to, in order to cause the piston to reciprocally move in the axial direction through the shaft, convert rotational movement of the motor section to linear movement, and output the linear movement from the output axle to the shaft; a guiding member (7, 107) which is placed on the other axial end side of the interior of the housing with respect to the piston, which is attached to the housing, and which is able to guide the shaft in a manner to be movable in the axial direction; and a restricting mechanism (8, 108) which is disposed in the housing and between the guiding member and the shaft, and which is able to restrict rotation of the shaft about the axis while allowing reciprocal movement in the axial direction, wherein the restricting mechanism comprises a member (61,162) having a plurality of rolling elements in the member for reducing rattling during movement of the shaft. a housing (2, 102); a piston (3, 103) which is placed in the housing to be coaxial with the housing, and which is disposed to be reciprocally movable in an axial direction of the housing; a shaft (4, 104) which is configured to be moved in conjunction with the piston in a state where one axial end side is in contact with the piston; a rolling diaphragm (5,105) having: a lid portion (35, 135) which is placed on the one axial end side of the piston; an open-end portion (36, 136) which is attached to the housing; and a folded portion (37, 137) which is placed between the lid portion and the open-end portion, the lid portion being reciprocally movable integrally with the piston with respect to the open-end portion which is positionally fixed by the housing; a pump chamber (51, 151) which is defined by the rolling diaphragm on a one axial end side of an interior of the housing with respect to the rolling diaphragm, a volume of an interior of the chamber being variable; a driving device (6, 106) having: a motor section (30, 130); and an output axle (31, 131) which is placed coaxially with the shaft, and which is coupled to another axial end side of the shaft, the driving device being attached to another axial end side of the housing, the driving device being able to, in order to cause the piston to reciprocally move in the axial direction through the shaft, convert rotational movement of the motor section to linear movement, and output the linear movement from the output axle to the shaft; a guiding member (7, 107) which is placed on the other axial end side of the interior of the housing with respect to the piston, which is attached to the housing, and which is able to guide the shaft in a manner to be movable in the axial direction; and a restricting mechanism (8, 108) which is disposed in the housing and between the guiding member and the shaft, and which is able to restrict rotation of the shaft about the axis while allowing reciprocal movement in the axial direction, wherein the restricting mechanism comprises a member (61,162) having a plurality of rolling elements in the member for reducing rattling during movement of the shaft.