To prevent a tank of a direct-current high-voltage power source from corroding by separating an irradiation area where an object is irradiated with an electron beam from a direct-current voltage or a cable connection tank with a barrier that is made of a highly anticorrosive material and prevents the air from flowing.

An irradiation area 12 and a barrier 22 are located in a box 2. In the area 12, an object 8 is irradiated with an electron beam 8. Between the irradiation area 12 and a direct-current high-voltage power source 14 provided is the barrier 22 for inhibiting the air from flowing there. The barrier 22 separates the irradiation area 12 from the power source 14. The barrier 22 is made of a highly anticorrosive material; for example, stainless steel. Since such a structure allows the barrier 22 to block the ozone generated in the irradiation area 12 and disable it from reaching the direct-current high-voltage power source 14, the ozone can prevent a tank 15 of the power source 14 from corroding.