a fixed body in which a pump chamber in communication with a fluid suction port and a fluid discharge port is constructed;

a valve element for expanding and contracting an internal volume of the pump chamber to perform suction and discharge of fluid; and

a drive mechanism for driving the valve element which comprises:

a ring-shaped stator including a coil;

a rotation body including a rotor magnet whose peripheral face faces a peripheral face of the stator;

a movable body to which the valve element is fixed; and

a conversion mechanism in which rotation of the rotation body is converted to movement of the movable body in the axial direction, which comprises:

a power transmitting mechanism which is provided with a screw groove or a cam groove between the rotation body and the movable body; and

a co-rotation preventive mechanism which prevents the movable body from co-rotating with the rotation body;

wherein the rotation body comprises a cup-shaped member that is coaxially disposed on an inner side of the stator;

the movable body is provided with a cylindrical center part at a center of the movable body that is coaxially disposed on an inner side of the cup-shaped member;

the valve element is a diaphragm valve that partitions the pump chamber;

an outer peripheral edge part of the diaphragm valve is fixed to the fixed body;

a center part of the diaphragm valve is fixed to the cylindrical center part of the movable body;

a cylindrical body part between the outer peripheral edge part and the center part of the diaphragm valve is disposed so that a U-shaped portion is formed on the inner side of the cup-shaped member of the rotation body; and

the U-shaped portion of the cylindrical body part is moved on the inner side of the cup-shaped member of the rotation body when the internal volume of the pump chamber is expanded and contracted by the diaphragm valve.