A scroll compressor includes an orbiting scroll engaged with a front case by pins and rings or ring holes to prevent rotation of the orbiting scroll. The rings or the ring holes have such an inside diameter that an orbiting radius defined by the pins and the rings or the ring holes is larger than a theoretical orbiting radius defined by engagement between gear surfaces of a fixed scroll and the orbiting scroll. The pins, the rings, or the ring holes are shifted in such a direction as to relieve twisting of the orbiting scroll relative to the fixed scroll.