Breakage in a short period is suppressed by improving a heat dissipation property.A glow plug (1) that includes: a heater (11), a tip of which is inserted in a combustion chamber of an internal combustion engine; a cylindrical body (12) that supports abase end of the heater; a housing (14) that supports the cylindrical body in a state where a heating section of the heater is projected; and a pressure sensor (15) that is provided in the housing and detects a pressure in a combustion chamber includes: a pressure introduction chamber (142) that is formed between the pressure sensor and the cylindrical body in the housing; and a communication path (21) that is formed in at least one of the housing and the cylindrical body and communicates between the combustion chamber and the pressure introduction chamber.