To provide a high-voltage transformer, capable of generating a high voltage output with no fear of contact between upper and lower layers in an inside of a winding separated by separation.

A coil bobbin 1 has each brimmed part 3 provided at both ends of a tube-shaped core 2 made of an insulating material, and a separator 5 for separating a winding between these brimmed parts 3. In this case, the separators 5 have a slanted side face in a way such that a space between the separators 5 becomes smaller the nearer it approaches the core 2. A winding is provided around the coil bobbin 1, and a core 10 is inserted to form a transformer.