To provide a centrifugal molding process for preparing an endless sheet-like resin belt used as an intermediate transfer belt for a photographic image forming apparatus, etc., and especially, a method for preparing an endless resin belt with good edges and by the centrifugal molding process improving its productivity.

In this method for preparation, when a resin soln. 3 is fed in a cylindrical centrifugal mold 1 rotating in the horizontal axial direction and the resin soln. 3 is centrifugally applied on the inside face of the mold 1 to form an endless sheet-like resin belt, ring-like edge-dams 2 for preventing the resin soln. 3 from sagging caused by extending and flowing are mounted on the peripheral edge sites on both sides of the mold 1 to perform molding.