In a stator of an electric rotating machine such as a motor, there is provided with laminated 24 yoke pieces that form a yoke of circular shape when assembled and the yoke pieces are made rotatable relative to each other. At that time, a roller presses another roller and a separation pad holder through a separation roller and a sheet which is separated by the separation pad, and a pressure welding pressure between the separation roller and the separation pad is reduced. A first function of one of the one or more targets over the one or more registers and the one or more inputs is computed.