To improve productivity in a method for molding a cylindrical base material in which a circumferential thin part is formed on the cylindrical base material for a steel wheel by plastic working.

The cylindrical base material W is supplied and supported between a movement restricting cylinder 22 and a fastening cylinder 31 by a supply and support mechanism 4 so that an axis of the cylindrical base material W coincides with axes of a spindle 20 of a spindle mechanism 2 and a rotating shaft 30 of a tailstock mechanism 3, and the cylindrical base material W is fastened by the movement restricting cylinder 22 and the fastening cylinder 31 in the state that the spindle 20 of the spindle mechanism 2 and the rotating shaft 30 of the tailstock mechanism 3 are rotated, and the cylindrical base material W is attached to a die 21, and movement restriction of the other end side W2 of the cylindrical base material W by the fastening cylinder 31 is released, and plastic working is performed on an outer peripheral surface of the cylindrical base material W by a forming roller R, and then, the die 21 is retreated in the movement restricting cylinder 22 in the state that the spindle 20 of the spindle mechanism 2 is rotated, and thus, the cylindrical base material W to which plastic working is performed is released from the die 21.