PURPOSE: To normally operate a vane by a method wherein a compressor part to perform compression orderly in two stages is mounted in a closed container, the interior of the closed container is filled with a first stage delivery pressure, and an introduction passage for intercommunicating a second stage delivery valve chamber and a vane back pressure chamber is formed.

CONSTITUTION: An electric motor part 2 and a compressor part having two compression chambers compressed orderly in two stages by means of the electric motor part 2 are provided in a closed container 1. The interior of the closed chamber 1 is filled with a first stage delivery pressure, and a vane back chamber 15 is formed with a second stage cylinder vane groove, a vane back, a middle plate 5, and a bearing end plate 6. The second stage delivery valve chamber 16 is communicated with the vane back chamber 15 through an introduction passage 17. This constitution causes the passage of a high pressure refrigerant, delivered in the second stage delivery valve chamber 16, through the introduction passage 17 and flows in the vane back chamber 15 which is filled with a second stage delivery pressure. The refrigerant is exerted in a manner to produce a force, which presses a second stage vane 13 from the back. Thus, a back force being high enough to beat a pressure in a second stage compression chamber is produced, and an effect to normally work a vane 13 is produced.