In a power transmission apparatus for a compressor according to the present invention, a package of the compressor is reduced in size by shortening the longitudinal length of a one-way bearing while a predetermined level of transmission torque is sustained by optimizing the locations of the one-way bearing and a ball bearing module. Therefore, the mountability thereof can be improved. Also, the one-way bearing is disposed at an outer side from the ball bearing module in a radial direction so as to increase the number of rollers constituting the one-way bearing. Therefore, the transmission torque can be kept identically to that of the related art although the length of the one-way bearing is shortened.