PURPOSE: To stratify the air-fuel mixture in an effective manner, by determining the injection starting time of a fuel injection valve disposed in an intake passage through addition and subtraction of a basic injection timing and an intermediate time obtained as a function of the engine speed and the injection time.

CONSTITUTION: In operation of an engine, a basic injection time τp is at first calculated at a CPU23 from the outputs of an air-flow meter 3 and a crank- angle sensor 17. Then, an effective injection time τe is calculated by correcting the basic injection time τp according to the temperatures of cooling water, intake air, etc. and a fuel injection time τi is obtained by adding a fixed value of an ineffective injection time τv to the injection time τe. Thereafter, an intermediate time ΔInj is obtained by reading a fixed value of a basic injection timing Inj0 and calculating ΔInj1 and ΔInj2 respectively from the engine speed and the fuel injection time τi. Further, a fuel injection starting time θ is calculated from a formula, θ=ΔInj0-ΔInj, and injection valve driving circuits 18aW18d are controlled according to the value θ.