A method for restarting an induction machine in a process of restoring power, comprising: estimating a position of a rotor and a speed thereof when a driving signal is supplied to an induction machine after power is restored; resetting a speed reference to correspond to the estimated speed of the rotor; generating a control voltage corresponding to the reset speed reference; characterized by: estimating, in a speed estimation section, Mode 2, a rotor counter electromotive force, using the estimated rotor counter electromotive force in the estimating of the position of the rotor and the speed thereof, wherein the estimated rotor counter electromotive force is used as a voltage reference when estimating the speed of the rotor; regulating, in a voltage regulation section, Mode 3, a voltage magnitude using the estimated rotor counter electromotive force and a voltage reference generated to correspond to the control voltage, wherein regulating the voltage magnitude comprises gradually regulating the voltage magnitude from a magnitude of the estimated rotor counter electromotive force to a magnitude of the voltage reference generated to correspond to the control voltage; and re-accelerating, in a re-acceleration section, Mode 4, the induction machine up to a target speed after the voltage magnitude has been regulated. estimating a position of a rotor and a speed thereof when a driving signal is supplied to an induction machine after power is restored; resetting a speed reference to correspond to the estimated speed of the rotor; generating a control voltage corresponding to the reset speed reference; characterized by: estimating, in a speed estimation section, Mode 2, a rotor counter electromotive force, using the estimated rotor counter electromotive force in the estimating of the position of the rotor and the speed thereof, wherein the estimated rotor counter electromotive force is used as a voltage reference when estimating the speed of the rotor; regulating, in a voltage regulation section, Mode 3, a voltage magnitude using the estimated rotor counter electromotive force and a voltage reference generated to correspond to the control voltage, wherein regulating the voltage magnitude comprises gradually regulating the voltage magnitude from a magnitude of the estimated rotor counter electromotive force to a magnitude of the voltage reference generated to correspond to the control voltage; and re-accelerating, in a re-acceleration section, Mode 4, the induction machine up to a target speed after the voltage magnitude has been regulated. estimating, in a speed estimation section, Mode 2, a rotor counter electromotive force, using the estimated rotor counter electromotive force in the estimating of the position of the rotor and the speed thereof, wherein the estimated rotor counter electromotive force is used as a voltage reference when estimating the speed of the rotor; regulating, in a voltage regulation section, Mode 3, a voltage magnitude using the estimated rotor counter electromotive force and a voltage reference generated to correspond to the control voltage, wherein regulating the voltage magnitude comprises gradually regulating the voltage magnitude from a magnitude of the estimated rotor counter electromotive force to a magnitude of the voltage reference generated to correspond to the control voltage; and re-accelerating, in a re-acceleration section, Mode 4, the induction machine up to a target speed after the voltage magnitude has been regulated.