A rotary machine control apparatus includes: a current detector detecting an alternating current flowing through a rotary machine and outputting a current detection value; a power converter supplying power to the rotary machine by applying an AC voltage based on a voltage command value; a current controller adjusting the voltage command value so that the current detection value matches a current command value; an estimator obtaining a magnetic-flux estimation value that is an estimation value of an amplitude of a magnetic flux vector in the rotary machine; and a magnetic flux controller adjusting the current command value so that the magnetic-flux estimation value matches a set magnetic-flux command value in a start-up control period from when the rotary machine is put in a state where the rotary machine rotates by inertia after interruption of power supply of the power converter until the power supply is resumed.