PURPOSE: To increase the degree of sealing in the axial direction by returning a compressed fluid to the suction port side of the fluid through a connecting port having a throttling effect and via the space between a movable scroll member and a housing.

CONSTITUTION: Part of a compressed fluid is returned to the suction passage side of the fluid via the space 31 between a movable scroll member 20 and a housing 30. Thereby, back pressure acts on the side plate 21 of the movable scroll member 20. This back pressure acts so as to closely attach the movable scroll member 20 to a fixed scroll member 10 in the axial direction. Further, since the fluid introduced into the space between the movable scroll member 20 and the housing 30 is introduced via a passage 15 having a throttling effect, the space is kept in a uniform pressure during the operation of a compressor.