Control of a brushless DC motor which has a plurality of windings and a rotor with a plurality of magnetic poles, is accomplished by sucessively feeding the current for driving the rotor to the windings to rotate the motor. The voltage of a power source that supplies the current is measured, a threshold current level for detecting the position of the rotor relative to the winding is set based on the measured voltage, the current supplied to the winding is limited and permitted to flow again into the same winding while the rising condition of current is measured, the measured rising condition is compared with the threshold level to determine switching of the current to the next winding, and the control is repeated when it is determined that the current should not be switched to the next winding.