An inverter, motor drive device and freezing device, with which it is possible to effectively suppress current beats in the event of over-modulation without requiring additional circuits. This motor driving device includes: a rectifier circuit that converts the AC voltage from an AC power supply into a DC voltage; a smoothing capacitor that smoothes the DC voltage output from the rectifier circuit; an inverter circuit that converts the DC voltage output from the smoothing capacitor into an AC voltage; and a controller that reduces the current beat component by estimating, using a phase locked loop process, the frequency, phase and amplitude of the current beat component in the output current of the inverter circuit, and corrects the voltage command to the inverter circuit on the basis of the estimated frequency, phase and amplitude.