Ceramic heater and glow plug having the same

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PROBLEM TO BE SOLVED : To provide a ceramic heater and a glow plug to install this, having a sufficient folding endurance strength, and having small dispersion. SOLUTION : An exothermic resistor wherein conductive ceramic particles consisting of silicide, carbide of metal element such as W, Ta, Nb or the like are dispersed in a matrix ceramic phase consisting of silicon nitride sintered body or the like, and a lead wire which is composed of metal of W, Re, Ta or the like, or an alloy or the like that has those metals as the main component, and which is fitted to an end brim of the exothermic resistor are embedded into a base body consisting of a silicon nitride sintered body or the like to compose the ceramic heater. In this ceramic heater, by specifying a mass ratio of a rare earth element contained in the exothermic resistor and base body, the ceramic heater is obtained in which the thickness of an unevenly formed layer is not more than 5 μm while a specified component, especially the rare earth element unevenly exists, or the ceramic heater in which such an unevenness does not exist is obtained.