PURPOSE: To treat a part of long size structure with minimum expense, by arranging metal vessel in receiving vessel and introducing the part of the structure to be treated and then, placing the inner electrode in the metal vessel.

CONSTITUTION: The metal vessel 3 is provided in the inner part of the receiving vessel 1 and electric potential of the vessel 3 is made the same to that of the vessel 1. The inner electrode 4 is provided in the vessel 3 and the supply device 5 is penetrated into the wall of the vessel 3 and 1 and then, is insulated by the insulating device 6. The structure 8 is inserted in the vessel 3 penetrating the wall of the vessel 1 and the part to be treated is wrapped and surrounded by the pot-shaped body 7 of the electrode 4. The vacuum leakage stopping device 9 is provided on the opening part of the vessel 1. Temperature of the part of the structure 8 to be treated is risen by glow discharge by direct or indirect heating.