In a rotor hub manufacturing method, a workpiece is chucked and a hole centering on the workpiece center axis is formed in the workpiece. A sealing member is press-fit into the hole, forming an internal space. A shaft feature is thereafter shaped in the workpiece by cutting work done on the periphery of the workpiece around the hole. The workpiece part including the shaft feature is then cut away from the workpiece to form a rotor hub as a shaft unit.