A movable scroll element for a scroll type compressor is produced by a combination of a mold casting process and a machining process. The mold casting process produces a cast product having an end-plate forming portion, a spiral-member-forming portion and a projecting portion for forming a drive power receiving portion. The cast product has an entire outer faces covered with black scale, and the machining process machines the end-plate-forming portion, a spiral member forming portion, the projecting portion by cutting. Nevertheless, at least an outer circumference of the drive power receiving portion, i.e., a boss portion of the movable scroll element is covered with an outermost layer consisting of black scale. Thus, a sufficient mechanical strength of the movable scroll element is obtained even if the wall thickness of the drive power receiving portion, i.e., the boss portion of the movable scroll element, is reduced.