A scroll material 160 for the production of a scroll is cast, a scroll portion 54 thereof is left as cast, and the portions other than the scroll portion 54 are machine-worked. Positioning portions 168, 169, and 170 and an engagement hole 172 are cast together with the scroll portion 54 of the scroll material 160, etc., in a die-casting process. In a machine working process, an engagement portion 248 of a holding jaw 234 is engaged with the engagement hole 172 of the positioning portion 168 and at the same time the positioning portions 168, 169, and 170 are held with the holding jaws 234, 236 and 238 of a chuck 230. In this state, the outer side surface of the base 162 opposite to the scroll portion 54, etc., are cutting-worked with work tools. Using the positioning portions 168, 169, and 170 as the work basis is almost equal to using the scroll portion 54 as the work basis, and a movable scroll, having a high relative positioning accuracy between the scroll portion 54 and other portions, can be manufactured.