In a scroll compressor enclosed in a casing and a movable scroll member is driven eccentrically by an electric motor, a thrust force created by the compression and applied to the movable scroll member is cancelled by a high pressure chamber which is provided between a surface of the movable scroll member and a frame member and supplied with a pressurized gas delivered from the scroll compressor. The high pressure chamber is formed into an annular shape defined by radially inner and outer tapered walls, and radially inner and outer seal rings having resilience to shrink and expand respectively are provided in the chamber for preventing leakage of the gas out of the high pressure chamber.