In a forming method for forming an assembly of a bead core and an apex rubber, there is used a rotating body which comprises a rotating base substance having an assembly forming surface, and a core receiving portion projecting from the rotating base substance in the axially outward direction of the rotating base substance. The core receiving portion projecting has a receiving surface supporting the radially inner peripheral surface of the bead core. The apex rubber is formed by winding an unvulcanized rubber strip along the assembly forming surface from a starting position constituted by the radially outer peripheral surface of the bead core supported on the receiving surface so as to laminate in a tapered cross sectional shape.