Provided is an X-ray apparatus and a method of controlling an X-ray apparatus capable of detecting a sign of breakage of a filament. A method of controlling an X-ray apparatus 1 for performing controlinvolving controlling a filament current flowing through a filament 4 of a cathode part 5 to maintain constant a tube current flowing between the cathode part and an anode part 7 with a target 6, includes: monitoring the current value of at least one of the filament current and the tube current; detecting the mode of change in the current value; determining the presence or absence of a sign of breakage of the filament 4 based on the mode of change in the current value; and issuing a warning based on the determination.