A control system for an internal combustion engine comprising: an internal combustion engine having a combustion chamber; an injector provided for said combustion chamber to directly inject fuel and produce an air fuel mixture therein; an ignition plug provided for said combustion chamber to ignite said air fuel mixture; and a controller to operate said internal combustion engine selectively between a homogeneous combustion mode and a stratified stoichiometric combustion mode in response to an engine operating condition, and to adjust fuel injection quantity (CTiS) so as to reduce a change (a) of engine torque due to said combustion mode being converted, wherein, the stratified stoichiometric combustion mode is a stratified combustion mode with an average air fuel ratio in the combustion chamber set at the approximately stoichiometric ratio and in a case of converting said stratified stoichiometric combustion mode to said homogeneous combustion mode, said controller gradually increases said fuel injection quantity (CTiS) from an occurrence of a request until said combustion mode is converted, then adjusts said fuel injection quantity (CTiS) in a decreasing direction to an amount without adjustment (CTiS0) when said combustion mode is converted, and in a case of converting said homogeneous combustion mode to said stratified stoichiometric combustion mode, adjusts said fuel injection quantity (CTiS) in an increasing direction when said combustion mode is converted, then gradually decreases said fuel injection quantity (CTiS) to a basic fuel injection quantity (CTiS0) determined according to present engine operating conditions. an internal combustion engine having a combustion chamber; an injector provided for said combustion chamber to directly inject fuel and produce an air fuel mixture therein; an ignition plug provided for said combustion chamber to ignite said air fuel mixture; and a controller to operate said internal combustion engine selectively between a homogeneous combustion mode and a stratified stoichiometric combustion mode in response to an engine operating condition, and to adjust fuel injection quantity (CTiS) so as to reduce a change (a) of engine torque due to said combustion mode being converted, wherein, the stratified stoichiometric combustion mode is a stratified combustion mode with an average air fuel ratio in the combustion chamber set at the approximately stoichiometric ratio and in a case of converting said stratified stoichiometric combustion mode to said homogeneous combustion mode, said controller gradually increases said fuel injection quantity (CTiS) from an occurrence of a request until said combustion mode is converted, then adjusts said fuel injection quantity (CTiS) in a decreasing direction to an amount without adjustment (CTiS0) when said combustion mode is converted, and in a case of converting said homogeneous combustion mode to said stratified stoichiometric combustion mode, adjusts said fuel injection quantity (CTiS) in an increasing direction when said combustion mode is converted, then gradually decreases said fuel injection quantity (CTiS) to a basic fuel injection quantity (CTiS0) determined according to present engine operating conditions.