A high-voltage device according to embodiments comprises an inverter circuit configured to convert a direct-current voltage into an alternating-current voltage, a high-voltage transformer, an insulating layer and a conductive layer. The high-voltage transformer includes a primary coil on an input side and multiple secondary coils on an output side and raises a voltage of output of the inverter circuit. The insulating layer is provided on an outer circumference of a bundle of winding wires of each of the secondary coils so as to individually cover each of the secondary coils The conductive layer is provided on an outer circumference of each of the insulating layers so as to individually cover each of the insulating layers.
