It is an object to enable efficient driving even if the rotation speed is variable in a driving circuit for a DC brushless motor having no position detection. The counterelectromotive force of the motor M is received by the comparators (201-203) and the trigger signals (G1 and G2) are outputted with 120.degree. cycle in synchronization with the rotation. Two oscillation signals (N1 and N2) in synchronization with the rotation of the motor are generated therefrom and a serial control signal (CNT) which becomes active/inactive for every 30.degree. is further produced in the 30.degree. signal operation circuit (104). The control signal (CNT) is serial/parallel converted into conversion control signals (L1-L3) in the 180.degree. signal conversion circuit (105). The 120.degree. switching circuit (1116) further converts them into driving signals (K1-K6) and applies them to the current control portion (300). The motor is driven by a signal delayed by a rotation angle of 30.degree. not according to the number of rotation of the motor.