PURPOSE: To prevent bad influence from an intake cylinder to an operational cylinder to the possible extent by stopping fuel supply to a part of cylinders at a required time and performing correction of air-fuel mixture in parallel with variation fuel injection characteristic in the case of correcting supply of air-fuel mixture to the other cylinders which continuously operate.

CONSTITUTION: A multiple-cylinder internal combustion engine 11 is used for a outerboard motor 10 for example, and a combustion chamber 13 is formed inside a cylinder 12. A fuel injection nozzle 27 is arranged in an intake passage 25, and is connected to a fuel system 40, and controlled by an engine control computer ECU. Additionally, engine load is calculated by an ECU based the basis of the opening of a throttle valve 28 and the speed of a crank shaft 21, so as to calculate a fuel supply quantity. Fuel supplied into a part of the cylinders at the time of low-speed low-load operation is temporarily stopped in, and supply of air-fuel mixture to the remaining cylinders continuously operated is corrected by the ECU. In this case, the operation for correcting the air-fuel mixture is carried out together with changing of fuel injection characteristic by the fuel injection nozzle 27.