The invention relates to a control device used in motivation type DC driving motor in printing machine or other machines. The control device comprises a component which can generate filed current for magnetic field of the motor. The invention is characterized in that the component is connected with calculating equipment (12) and/or a measuring element which can adjust equipment and measure operational coefficient of a measuring motor (1). In accord with the result of the operational coefficient, the filed current can be equal to such result (measured value) so as to achieve preset working state. When armature voltage is relative to rotation speed (in given load), or armature current is relative to torque, the filed current is stabilizer at the measured value. The invention has the advantages of that the control device can correct valve of the filed current automatically. |