The invention concerns an ignition device for internal combustion engine, containing: a main chamber (1) designed for including a main combustible mixture, and fitted with a compression system of said mixture, an igniter (11) containing a precombustion chamber (2) designed for receiving reactants and an ignition system (13,14) of the reactants contained in the precombustion chamber, said precombustion chamber (2) being defined by a precombustion chamber body (12) having a head (12a) including at least one passageway (15), said head (12a) of the precombustion chamber body separating the precombustion chamber (2) from the main chamber (1) and communicating the precombustion chamber (2) and the main chamber (1) by dint of the passageway(s) (15), characterised in that said precombustion chamber body (12) is made of a material having a thermal conductivity at 20.degree. C. of at least 10 W/K/m.