Abstract: A drive system capable of driving a driven member with a large force and precisely rapidly positioning the same is disclosed, with use of a control unit for efficiently driving a motor with a large torque. Upon storage of target position data from a computer in a counter circuit of a driving mode switching circuit, the driven member is driven at a high speed with a large force via a ball screw/nut mechanism by the motor which efficiently operates as a two-phase reluctance motor at a high speed with large torque. When a count of the counter circuit, decremented with movement of the driven member, reaches a first preset value, supply of a sequence of position detection signals, indicative of the motor rotational position, to an energization control circuit is changed by a signal switching circuit, so that the motor is driven in the deceleration mode until its speed reaches a preset speed, and then the motor is driven at a constant speed.