To provide a means for increasing the compression ratio of a screw type gas pump for mainly blasting air with gas as the object, as a means with small pressure for increasing the compression ratio of a screw type gas pump and making it a compressor is not specifically revealed in other documents.

In the screw type compressor, a rod-like shaft is installed on the inside of a cylindrical sleeve, and a gap therebetween is set small. By rotating the shaft at a high speed, gas moving by being dragged on the surface of the shaft by its viscosity is guided into a high pressure part by a minute gap formed between a spiral rib and an opposing sleeve inner face or a shaft outer face, and the gas is compressed.