A compressor has a fixed scroll and a movable scroll which has a first surface and a second surface. The first surface is opposed to the fixed scroll to define a displaceable fluid pocket. The movable scroll is supported on a rotary shaft via an eccentric pin to move along a predetermined orbit around an axis of the rotary shaft. Gas is introduced into and compressed in the fluid pocket. A boss is formed with the second surface of the movable scroll. A bushing is supported on the eccentric pin and rotatably received by the boss. The rotary shaft has an inner end surface for securely supporting the eccentric pin. A holding member engages the eccentric pin to hold the bushing in a predetermined position on the eccentric pin in corporation with the inner surface of the rotary shaft. A balance weight is secured around the bushing to cancel a dynamic imbalance of the movable scroll due to the orbital movement of the movable scroll.