In a rotary machine control device for controlling a rotary machine having a multi-group multiphase configuration, a phase difference θcoil of 150° to 210° (excluding 180°) is electrically provided between a winding for an odd-number group and a winding for an even-number group in the rotary machine, wherein, when the effective value of a voltage command is smaller than a voltage threshold, the phase difference between the voltage commands for the respective groups is set to 180°, and when a torque command is greater than a torque threshold, the phase difference between the voltage commands for the respective groups is set to θcoil.