An object is to provide a rotor manufacturing method capable of reducing a rotor unbalance amount by controlling a magnet arrangement position in a rotor core and improving work efficiency when fixing a magnet to the rotor core by using resin. A lower surface of a rotor core is arranged in a lower mold. A magnet is arranged in a lower mold. A magnet is contained in each of magnet containing holes formed in the rotor core in such a manner that a predetermined space is assumed between an upper surface of the rotor core and an upper surface of the magnet. An upper mold is arranged on the upper surface of the rotor core. The upper mold and the lower mold apply a pressure to the rotor core and a molten resin is supplied with pressure from an internal diameter side via the predetermined space into the plurality of magnet containing holes from respective cylinder arranged in the upper mold. Thus, the magnets are molded by resin while pressing the magnets toward the outer diameter side of the magnet containing holes.