There is provided an automatic transmission control apparatus that secures the safety of a motor drive, even in the case where an abnormality exists in a unit that detects a voltage supplied to a motor control apparatus, and that neither deteriorates the controllability of the motor drive nor erroneously operates the transmission mechanism of the automatic transmission.An automatic transmission control apparatus according to the present invention is provided with a voltage determination unit that determines which one of a voltage detected by a control apparatus voltage detection unit and a voltage detected by a motor voltage detection unit is utilized as a duty reference voltage; the motor control apparatus controls the motor, based on a motor drive duty that a drive duty calculation unit calculates by use of the voltage determined by the voltage determination unit.