A rotary anode driving device includes a DC power supply, an inverter circuit which is connected to the DC power supply and includes a plurality of switching elements and, the inverter circuit generates an AC voltage from a DC voltage of the DC power supply, and outputs the AC voltage to a stator coil which generates a rotating magnetic field of an X-ray tube; a pulse width modulation (PWM) waveform generator configured to generate an AC voltage of two phases or three phases as the AC voltage from the DC voltage by performing PWM control of the switching elements of the inverter circuit; and a capacitor connected in series to an input side of a stator coil of at least one phase of the stator coil, the capacitor having an electrostatic capacitance constituting a series resonant circuit with the stator coil to which the capacitor is connected.