PROBLEM TO BE SOLVED: To reduce an operating cost by scarcely cracking, prolonging a useful period, and facilitating its maintenance therefor. SOLUTION: In the inner heat type electric furnace comprising a sintering space for receiving an object to be sintered at an inner center of a furnace body, a heater provided at a side of the space, and a reflector having a heater and installed to surround the space to sinter the object by a heat from the heater; the heat shielding plate is associated between the reflector of an outside of the heater and a furnace wall. The plate has a structure in which a plurality of alumina thin plates 50 each having a substantially rectangular shape, a cutout 52 formed from its lower side to the vicinity of its center and longitudinally split and laminated, an upper edge of the laminate sandwiched between U-shaped sections of a suppressing member 56 of a heat resistant metal and clamped by heat resistant bolts 58 and nuts 60 at the member and the cutouts pass heater leads.