An electric motor control method for executing either one of a current vector control and a voltage phase control in accordance with an operating state of an electric motor such that electric power to be supplied to the electric motor is controlled, the electric motor control method comprising: a current controlling step (S4-S6) of outputting a voltage command value (vdi*, vqi*) for the current vector control by calculating a feedback command value (vdi_fb*, vqi_fb*) and a feedforward compensation value (vd_dcpl*, vq_dcpl*) based on a torque command value (T*) for the electric motor, the feedback command value (vdi_fb*, vqi_fb*) being indicative of a voltage value for decreasing a deviation in a supply current to the electric motor, the feedforward compensation value (vd_dcpl*, vq_dcpl*) being a value for compensating the feedback command value (vdi_fb*, vqi_fb*); a switching controlling step (S8-S9) of initializing the voltage phase control based on a calculation value for the current vector control when a control on the electric motor is switched from the current vector control to the voltage phase control; and a voltage phase controlling step of outputting a voltage command value (vdv*, vqv*) for the voltage phase control by executing a feedback control on a predetermined voltage phase command value (αff*) based on the torque command value (T*) for the electric motor, characterized in that in the switching controlling step (S8-S9), a filtering process is performed on the feedback command value (vdi_fb*, vqi_fb*) such that a low-frequency component of the feedback command value (vdi_fb*, vqi_fb*) is passed, and an initial value (αflt*) for the voltage phase command value (α*) is calculated by use of the feedforward compensation value (vd_dcpl*, vq_dcpl*) and the feedback command value (vdi_fb*, vqi_fb*) on which the filtering process is performed. a current controlling step (S4-S6) of outputting a voltage command value (vdi*, vqi*) for the current vector control by calculating a feedback command value (vdi_fb*, vqi_fb*) and a feedforward compensation value (vd_dcpl*, vq_dcpl*) based on a torque command value (T*) for the electric motor, the feedback command value (vdi_fb*, vqi_fb*) being indicative of a voltage value for decreasing a deviation in a supply current to the electric motor, the feedforward compensation value (vd_dcpl*, vq_dcpl*) being a value for compensating the feedback command value (vdi_fb*, vqi_fb*); a switching controlling step (S8-S9) of initializing the voltage phase control based on a calculation value for the current vector control when a control on the electric motor is switched from the current vector control to the voltage phase control; and a voltage phase controlling step of outputting a voltage command value (vdv*, vqv*) for the voltage phase control by executing a feedback control on a predetermined voltage phase command value (αff*) based on the torque command value (T*) for the electric motor, characterized in that in the switching controlling step (S8-S9), a filtering process is performed on the feedback command value (vdi_fb*, vqi_fb*) such that a low-frequency component of the feedback command value (vdi_fb*, vqi_fb*) is passed, and an initial value (αflt*) for the voltage phase command value (α*) is calculated by use of the feedforward compensation value (vd_dcpl*, vq_dcpl*) and the feedback command value (vdi_fb*, vqi_fb*) on which the filtering process is performed. a filtering process is performed on the feedback command value (vdi_fb*, vqi_fb*) such that a low-frequency component of the feedback command value (vdi_fb*, vqi_fb*) is passed, and an initial value (αflt*) for the voltage phase command value (α*) is calculated by use of the feedforward compensation value (vd_dcpl*, vq_dcpl*) and the feedback command value (vdi_fb*, vqi_fb*) on which the filtering process is performed.