PURPOSE: To promote purification of exhaust gas and improvement of fuel consumption by a method wherein operation is carried out at each cylinder with lean combustion near the limit of stable operation by controlling a fuel injection device for each cylinder based on an average air-fuel ratio of all cylinders and unevenness in the combustion pressure of each cylinder.

CONSTITUTION: A whole region air-fuel ratio sensor 201 is disposed in the exhaust gas passage 200 of a multicylinder gasoline engine. A combustion pressure exerted on the spark plug 3 of each cylinder is detected by means of a combustion pressure sensor 5. Further, unevenness in the combustion pressure of each cylinder is detected by a combustion pressure unevenness circuit 4. Meanwhile, a fuel injection device 301 is disposed to each cylinder. The fuel injection device 301 is controlled by a control circuit 6 in such a way that the average air-fuel ratio of all cylinders is adjusted to a temporary lean air-fuel ratio and the temporary air-fuel ratio is rewritten to a target lean air-fuel ratio so that unevenness in the combustion pressure of each cylinder is set to a value below a stable operation limit decided by the limit of lean combustion.