To unify the temperature distribution of a furnace by a method wherein a heat generating body of silicon carbide, provided with non-generating parts of heat intentionally, is installed in the sectional direction of a tunnel type electric furnace.

A heat generating body of silicon carbide 1 is constituted of a heat generating part 6 at the central part thereof and non-generating parts of heat 6 at both end parts 8. When the heat generating body of silicon carbide 1 is used for a furnace, the heat generating body is inserted from the outside of a furnace body into the furnace and a part of both end units 8 is exposed to atmosphere or atmosphere approximated to a normal temperature at the outside of the furnace at all times. Accordingly, the temperature difference of several hundreds to one thousand and several hundreds degree is generated at all times between the heat generating part 6 in the furnace and the end parts 8, exposed to the outside of the furnace. Accordingly, a temperature difference is generated between the central part and end parts 8 (furnace walls) same as in the heat generating part 6 of the heat generating body of silicon carbide 1 in the furnace. The difference becomes several cm substantially from the furnace inner wall toward the inside of the furnace. Therefore, the non-generating part of heat 7, whose width is about 15-35% of effective heating width in the furnace, is provided at the central part of the heat generating part 6 of the heat generating body of silicon carbide whereby an area, wherein the temperature thereof is uniform, can be obtained efficiently.