A motor drive method which supplies a drive current in a pulse form to a multiphase motor, to drive the motor. The motor drive method includes the steps of: generating a pulse signal having a duty ratio in accordance with torque, alternately repeating an ON time-period and an OFF time-period in accordance with the pulse signal, to supply a drive current in a pulse form to a phase coil currently driving, interpolating back electromotive voltage of the OFF time-period (Toff), using a back electromotive voltage (Vu) of the ON time-period (Ton), with respect to the back electromotive voltage (Vu) occurring in at least one coil of the multiphase motor, to generate an interpolated virtual back electromotive voltage (Vu′), detecting a zero-cross point, by comparing the interpolated virtual back electromotive voltage (Vu′) with a midpoint voltage (Vcom) of the coil, to generate a BEMF detection signal (BEMF_EDGE), and switching a phase to be driven, based on the BEMF signal (BEMF_EDGE).