PURPOSE: To accelerate fuel atomization by pivotally supporting the basic edge onto the upstream side of a fuel adhesion part on the inner wall surface of a suction port and installing a flapper which holds the turning angle larger as the output becomes smaller and setting the turning edge of the flapper at the min. turning angle position so as to be opposed to the fuel adhesion part.

CONSTITUTION: A controller 22 executes the main routine of the engine control and executes a variety of subroutines at the same time. In the fuel injection routine, the injection timing is calculated on the basis of the engine revolution speed information and carries out fuel injection in an intake passage 10. When the opening degree control routine is reached, the operation state information is taken out, and the frapper opening degree θ is calculated, and opening degree correction is carried out on the basis of the map. The output electric current corresponding to the flapper opening degree θ is outputted into a flapper driving device 23, and the opening degree of a flapper 30 is kept. Therefore, the flapper can be kept at an optimum gap (t) according to a variety of operation states, and an eddy current in the vertical direction is allowed to flow down on a fuel adhesion part (a), and fuel atomization can be accelerated.