like corresponding to the transmitted force and a pressure generated in the combustion chamber or the like is measured based on the detection signal to measure a pressure generated in the inside of the combustion chamber with high accuracy it is necessary to ensure a state where the ceramic heater element 2 and the power transmission sleeve 28 are freely movable in the axial direction without being constrained by the housing 3 on the other hand to prevent a temperature of a brazing material used for bonding constitutional members and a temperature of the conductor portion 9 from being extremely elevated and exceeding a heat resistant temperature it is necessary to radiate heat generated by the ceramic heater element 2 by efficiently transmitting the heat to the housing 3 the glow plug 1 according to this embodiment is configured such that heat generated in the ceramic heater 7 is released to the housing 3 through the metal made flexible member 15 the glow plug 1 according to this embodiment adopts the seal structure which prevents the intrusion of an exhaust gas generated in the combustion chamber into a rear end side of the glow plug 1 outside the ceramic heater element 2 the flexible member 15 is bonded to the metal made outer sleeve 8 and the housing 3 thus ensuring airtightness of the glow plug 1 with respect to the combustion chamber on the other hand inside the metal made outer.