A compressor (20) is provided with compression mechanisms (61, 62) to have four compression chambers (61, 62, 63, 64) in total. In the compressor (20), the first compression chamber (61) and the second compression chamber (62) differ in the phase of capacity changing cycle from each other by 180° and the third compression chamber (63) and the fourth compression chamber (64) also differ in the phase of capacity changing cycle from each other by 180°. In a cylinder nonoperating mode, refrigerant is compressed in a single stage in each of the first compression chamber (61) and the second compression chamber (62) while the refrigerant compression operation is halted in the third compression chamber (63) and the fourth compression chamber (64). In a two-stage compression mode, refrigerant compressed in a single stage in each of the first compression chamber (61) and the second compression chamber (62) is further compressed in the third compression chamber (63) and the fourth compression chamber (64).