A scroll type fluid machine (1) including a rotation stopping mechanism (36) for stopping rotation of a movable scroll without hindering revolving motion of the movable scroll (16) relative to a fixed scroll (14) fixed to a casing (4), the rotation stopping mechanism includes: a support hole (42) drilled in either one of a base plate (16a) of the movable scroll and a pedestal part (4a) of the casing; a rotation stopping pin (38) that is fitted into the support hole, and is protruded to the side of the other of the base plate and the pedestal part; a restriction hole (46) drilled in the other of the base plate and the pedestal part, and loosely fitted with the rotation stopping pin; and a buffer member (44) interposed between the support hole and the rotation stopping pin.