A compressor capable of surely reducing, with an inexpensive structure, the possibility of occurrence of vibration and noise generated by the self-excited vibration of a suction valve when a flow is small, wherein an opening adjusting valve (40) installed in a refrigerant sucking flow passage (13c) leading to a cylinder (11a) is formed of an elastically deformable spiral member (41), and an interval between the spiral parts (41a) of the spiral member (41) is varied according to the flow of refrigerant to adjust the opening of the flow passage (13c), whereby the possibility of occurrence of the vibration and noise by the self-excited oscillation of the suction valve (14c) when the flow is small can be surely reduced, and the structure of the opening adjusting valve (40) can be simplified.