PURPOSE: To improve durability and contrive crack to be hardly generated by. posing a carbide forming layer formed when a roof tile piece is fumigated with a carbide interrupting section, of a carbide forming layer including a section forming a plurality of electrical conductive sections, and an outer peripheral carbide forming layer, which are interrupted from etch other.

CONSTITUTION: A roof tile piece is in a special shape on oxidizing it, and among carbide sections to be formed on the special surface of the fumigated roof tile piece, a central section on the rear side surface is interrupted from the other outer peripheral section, and the central section is electrified, and heat is generated. In other words, a roof tile moldings 19 is burned at a high temperature in a burning furnace, and a burned roof tile piece is formed, and continuously, propane gas, butane gas, or other combustion substance to be burnt at the time of the burning furnace within the temperature of 860-980°C and for generating residual carbon is burnt, and the fumigated roof tile piece having carbide forming layers on the front side surface and rear side surface of the roof tile piece is manufactured. After that, on the crape surface 10 of a recessed surface section 6 on the rear side surface of the oxidized roof tile piece, copper or copper allay is fused to be fusion-welded, and a plurality of conductive sections 7A, 7B are formed, and a stepped section 12 or other section for surrounding the conductive sections 7A, 7B is scraped off, and the carbide forming layer 13 of the recessed surface section 6 and the carbide forming layer of an outer peripheral are interrupted from each other at interrupting section 14.