Rotary machine control apparatus

A control apparatus includes: a current detection unit detecting rotary machine current flowing to a rotary machine; a position estimation unit calculating an estimate value of a rotor position based on the rotary machine current; a current control unit generating a first voltage command being a command value of rotary machine voltage for driving the rotary machine, based on a detection value of the rotary machine current and the estimate value of the rotor position; a position estimation voltage generation unit generating high-frequency voltage based on rotation information regarding direction of rotation of a rotor, the high-frequency voltage being a position estimation voltage for estimating the rotor position and having frequency higher than frequency of the first voltage command; and a voltage application device applying driving voltage to the rotary machine based on a second voltage command obtained by superimposition of the position estimation voltage on the first voltage command.