PURPOSE: To make lean stratified suction air formable in the whole combustion chamber and improve the combustibility, by constituting each fuel so as to be sprayed from an injector to a suction system at the valve opening initial stage and the closing state of a suction valve.

CONSTITUTION: An injector 4 intermittently spraying fuel out of a fuel tank is installed in a suction passage of a suction system, and this injection 4 is controlled by an electronic control unit 5 according to various driving conditions of an engine 1. In this case, the electronic control unit 5 is installed so as to operate and control the injector 4 each at the vale opening initial state and the closing stage of a suction valve 6 on the basis of information on various driving conditions. And, a lean mixture inside a combustion chamber 7 is almost uniformly diffused by primary combustive injection of the valve opening initial state of the suction valve 6, while fuel by secondary fuel injection at the valve closing period of the suction valve 6 is made so as to be left behind in and around a spark plug 9. With this constitution, improvements in ignitability and combustibility are promoted.