an x - ray computer tomography apparatus comprises a high - voltage transformer which performs the increase and noncontacting transmission of the power simultaneously and outputs a desired high voltage for causing x rays to be generated at the rotatable gantry section . the high - voltage transformer is divided into a primary - side which is provided on the static gantry section and to which the output of a frequency converting circuit is supplied and a secondary - side which generates a high voltage . a capacitor is connected to a secondary coil of the high - voltage transformer , thereby forming a resonance circuit .