chamber 7 moreover by making the nozzle hole 13 that faces the swirl chamber 7 an auxiliary nozzle hole having a very small diameter thus making the diameters of the fuel mist particles created by the nozzle hole 13 very small the evaporation and combustion can be further promoted this is particularly effective for improving the ease of cold start up and the stability of combustion the nozzle hole 14 that faces the main combustion chamber 5 need not necessarily be oriented in the direction of the swirl s2 but may be oriented in the counter flow direction so as to promote the evaporation of the fuel also a plurality of nozzle holes 14 may be provided each at a predetermined injection angle in this case the injection directions are preferably not toward the center of the main combustion chamber 5 it prevents abnormal combustion occurring at the combustion chamber center and suppresses the generation of nox which are due to the convergence of the swirl s2 at the center of the combustion chamber 5 and the hot air created thereat finally in explaining embodiments of the internal combustion engine combustion chamber according to the present invention the form of the main combustion chamber 5 thereof has been described as circular in horizontal section but polygonal forms such as squares or triangles which have corner areas 21 are also permissible as shown.