PURPOSE: To prevent inside surface of cylinder, outside surface of rotor and vane's surface, which slidingly contacts cylinder or rotor, from being worn out and also from adhesion of foreign matters, by covering them, at least either side of the surfaces which slidingly contact each other, with nonconductive high-hard thermal resistant material.

CONSTITUTION: By covering a tip 31 of the vane 3 and a side surface 32 with the nonconductive high-hard thermal resistant material, such as ceramic or thermit, etc., the vane's tip 31 and the cylinder's inside surface 11 and also the side surface 32 of the vane and a side surface 22 of the rotor groove which slidingly contact each other become prevented from metal-to-metal contact and provided with high wear-resistant capability. And further, by covering all of the cylinder's inside surface 11, the vane's tip 31, the side surface 32 and the rotor's outside surface with the nonconductive material to prevent electrodeposition of metallic ion on these surfaces, the wear-resistant capability become extremely improved. Further, since wall thickness of the vane 3 is thin, by using covering film thickness of 5W500μ, it becomes provided with high rigidity and excellent wear-resistant capability.