Disclosed is a scroll compressor. As two side surfaces of a rotation preventing member are formed to be flat with keys, the rotation preventing member, a main frame, and an orbiting scroll may be easily processed and partial frictions and noise due to the keys may be prevented. Furthermore, since the orbiting scroll is entirely and stably supported by a ring portion of the rotation preventing member, the occurrence of a tilting moment of the orbiting scroll may be reduced. This may enhance the stability and the performance of the scroll compressor.