The invention relates to a spark-ignition internal combustion engine comprising a combustion chamber, a fuel injection means (13) for injecting fuel, an air amount control means (28) for controlling intake air amount into a combustion chamber (7), an ignition means (14) for igniting the mixture of air and fuel in said combustion chamber (7) and an engine controlling means (5) coupled to said fuel injection means (13), said air amount control means (28) and said ignition means (14), respectively, wherein said engine controlling means (5) has a first control mode in which an engine torque is changed when an air/fuel ratio is varied and a second control mode in which the engine torque is changed by controlling a throttle valve (22) while maintaining a substantially fixed air/fuel ratio, the engine torque in the second control mode is smaller than a predetermined value and the engine torque in the first mode is larger than said predetermined value.