Ceramic heater

PURPOSE : To solve problems in use at a high temperature of around 1400 deg.C by adding a specified amount of a rare earth element oxide as a sintering assistant to a supporting body and a heating body both comprising a mixture sinter of conductive ceramic and insulating ceramic. CONSTITUTION : A supporting body of a ceramic heater becomes an insulator by enclosing conductive ceramic particles with insulating ceramic particles, and a heating body formed at the tip of the supporting body becomes a conductor by oppositely constituting. At least one X, Ywt.% rare earth element oxide is added to the heating body and the supporting body respectively, X, Y are decided based on the inequality of X>=0.7>=Y, and the total adding amount is 3-25wt% of the total ceramic weight. When the heater is used at around 1400 deg.C for a long time, increase in resistance is suppressed, and in addition, elute of glass and generation of cracks are suppressed. Use of silicon nitride is preferable as the insulating ceramic, and the conductive ceramic is selected from carbide, silicide, nitride, and boride of metal.