PURPOSE: To protect transistors in an inverter circuit for driving a brushless motor against deterioration and breakdown.

CONSTITUTION: A voltage induced in the armature winding U of a brushless motor 5 is inputted to a position detecting circuit 6 where it is compared with a predetermined reference voltage. A comparison result signal is fed to a microcomputer 10a where a conduction switching timing for the brushless motor 5 is calculated. In such control method for brushless motor the microcomputer 10a stops the brushless motor 5 when the edge (the first edge after spike voltage) of the comparison result signal (positional detection signal) from the position detecting circuit 6 is not detected for a predetermined time after switching the conduction.