To provide a heat-treating furnace, in which flow of current by discharge is prevented between electric heaters used for furnace heating means by discharge.

A product as the subject is heat-treated in vacuum or a gas atmosphere of group-0 elements in the periodic table at temperature of 1,100°C or over. A plurality of the electric heaters are disposed in this heat-treating furnace of a batch type. The heat-treating furnace is composed in such a circuit that every other ones of the electric heaters are electrically insulated.