PURPOSE: To prevent a refrigerant conveying pump from the internal leakage by setting an axial clearnace between two bearings and a rotor to 20W60μ.

CONSTITUTION: The rotation of a motor 8 rotates a magnet 9 mounted on a motor shaft 5 while rotating a rotor shaft 5 through a magnet 10. By the slide of vanes 7 along the inner peripheral surface of a cylinder 3, two ports A, B provided in the cylinder 3 serve respectively as intake and discharge ports to carry out a pumping action. An axial clearnace between two bearings 1, 2 and a rotor portion of the rotor shaft 5 is set to 20W60μ so that a refrigerant conveying pump can be prevented from the internal leakage.