Provided is a motor driver including: a converter that converts an AC voltage into a DC voltage; an inverter that inverts the DC voltage into a multi-phase AC voltage for motor driving; a short bar fixed to an output terminal of the converter and an input terminal of the inverter by screw fastening; a first voltage detector that detects a voltage across the output terminals of the converter; a second voltage detector that detects a voltage across the input terminals of the inverter; and a reporting unit that provides, when a difference between the voltage detected by the first voltage detector and the voltage detected by the second voltage detector exceeds a predetermined threshold, a report relating thereto.