To provide a power transmission mechanism which can suppress dispersion of a release torque while miniaturizing the configuration.

A power transmission mechanism PT of a refrigerant compressor connects a pulley 64 rotatably supported on a front housing 12 through a bearing 60 with a hub 67 coupled to a rotary shaft so as to be power-transmittable. The power transmission mechanism PT is equipped with a one-way clutch 70, wherein an inside clutch member of the one-way clutch 70 is formed of the outer ring 63 of the bearing 60. The outer ring 63 is integrally rotatably coupled to the pulley 64 by a coupling part 63a of the front housing 12 rather than by a portion taken as the inside clutch member in the outer ring 63. The inner peripheral surface 71B of an outside clutch member 71 is integrally rotatably coupled with the hub 67.