A screw compressor in which noise and vibration caused by a variation in compression torque are effectively reduced. The screw compressor (1) has a first meshing body (2) and second meshing bodies (5, 6). The first meshing body (2) has helical grooves (11) around a first rotating shaft (4). The second meshing bodies (5, 6) have projections (12) or ridges formed around second rotating shafts (8, 9). At least one projection (12) or ridge of each second rotating shaft (8, 9) is placed irregularly in the circumferential direction with respect to the other projections (12) or ridges. The helical grooves (11) are arranged in the circumferential direction in the first rotating shaft (4) so as to be able to mesh with the projections (12) or ridges.