A residual gas control apparatus for internal combustion engines of the type including a main combustion chamber connected through a torch passage to an auxiliary combustion chamber having a spark plug, the residual gas control including a partial partition dividing the auxiliary combustion chamber into a first zone exposed to the spark plug and a second zone exposed to the torch passage, there being openings connecting the two zones, the partition and openings serving to control the percentages of residual gas in the two zones so as to produce optimum ignition and reduce NOx generation, and also to minimize turbulence in the vicinity of the spark plug.