A motor driving control apparatus is provided. In related art technique, an average neutral point voltage is detected via a low-pass filter lower than a PWM frequency, and this average value is compared with a predetermined threshold value to detect an abnormality such as a short circuit to ground of the motor. A higher harmonic component depending on a modulated signal is superimposed on the neutral point voltage of the motor, so that time constant needs to be set to cover the entire output frequency band of the inverter, and a voltage fluctuation due to an inverter modulation scheme needs to be separated from a voltage fluctuation due to a short circuit to ground. According to the present invention, whether abnormality such as a short circuit to ground or to supply occurs in output lines can be determined based on an actual neutral point voltage of a motor, which changes in a stepwise fashion in conformity to a PWM pulse pattern output by an inverter device, and a normal neutral point voltage which depends on a PWM pattern output by the inverter device. Highly reliable abnormality detection in accordance with the waveform of the neutral point voltage and stable abnormality detection not depending on the inverter output frequency are feasible.