The invention provides rotation recognizing means recognizing the rotating amount of a crankshaft by cylinders before the combustion cycle of a cylinder concerned. When the injection and supply of a fuel from an injector into the cylinder of the six cylinders are disabled, the number of the cylinders to be recognized by the rotation recognizing means is changed so that the rotating amount of the crankshaft for each of all the six cylinders in which the combustion cycles are continued to each other before the combustion cycle of the cylinder can be recognized. The supply of the fuel of the injector which supplies the fuel to the cylinders having a combustion cycle interval matching that of the cylinder to which the fuel cannot be supplied is controllably stopped so that the combustion cycle intervals between the cylinders on both front and rear sides of the fuel-unsupplied cylinder in the combustion cycle can be uniformed.