To provide an air conditioner's compressor structure that prevents a coefficient of air conditioner performance from being deteriorated for environmental protection's sake, for example, even in a compressive state of carbon dioxide and air or the like and even in the case where a refrigerant for maintaining a gaseous state, is used.

This is a compressor structure of an air conditioner equipped with a compressing means 1 adiabatically compressing refrigerant and an expanding means 3 adiabatically expanding this refrigerant, and this refrigerant is constituted so as to maintain a gaseous state even in a state that it is adiabatically compressed by the compressing means 1, while converting means 5 converting a pressure differential in the refrigerant before and after the expansion into kinetic energy and inputting it into the compressing means 1 as compressive driving force, is equipped in the expanding means 3.