a compressor has a movable scroll supported on a bushing connected to a rotary shaft via an eccentric pin . the movable scroll and the bushing are disposed coaxial to the eccentric pin to rotate together with the eccentric pin . the movable scroll moves along a predetermined circular path around an axis of the rotary shaft to closely contact a fixed scroll , opposed to the movable scroll at a given portion to define a displaceable fluid pocket and compresses refrigerant gas introduced into the fluid pocket . the compressor comprises a first balance weight eccentrically supported on the eccentric pin for an integral rotation therewith . the first balance weight is arranged to generate first centrifugal force counteracting second centrifugal force generated in the movable scroll and the bushing based on the rotation of the movable scroll and the bushing . the first balance weight has a weight in a predetermined ratio to weights of the movable scroll and the bushing to cancel substantially 80 to 97 percents of the second centrifugal force with the first centrifugal force . thus , the movable scroll is kept to move along the predetermined circular path .