Disclosed is an electric power consumption control system for a factory where a plurality of machine tools (Mi, Mp1, Mp2) are installed. A machine tool (Mi) is provided with a control device (10) whereby either the rotational acceleration/deceleration (Pi) for the motor for the machine tool and/or the rotational speed (Si) thereof is controlled on the basis of information regarding electric power consumption (Wt) in the factory so that electric power consumption will not exceed a specified value (We). This electric power consumption control system is also provided with electric power detection instruments (11, 12, 13) and an electric power monitoring instrument (20) which measure the electric power consumption of all the machine tools installed in the factory, thereby obtaining the electric power consumption of the factory, and provide information regarding the electric power consumption to the control device of the machine tool equipped with the control device.