The invention concerns an ignition device for internal combustion engine comprising: a main combustion chamber (1) fitted with a compression system; and an igniter (11) comprising a precombustion chamber (2) and an ignition system (13, 14), the precombustion chamber being defined by a precombustion chamber body (12) having a head (12a) including passageways (15), the head (12a) of the precombustion chamber body (12) separating the precombustion chamber (2) from the main chamber (1) and communicating the precombustion chamber (2) and the main chamber (1) through the passageways (15), characterized in that the passageways comprise at least one passageway enabling the propagation of a flame front of the precombustion chamber (2) to the main chamber (1) when the engine operates on low load and at least one passageway not enabling the propagation of a flame front while enabling the passageway of unstable compounds of the precombustion chamber (2) to the main chamber (1).