To solve the problem of being not compatible in both avoidance of a flow delay by sticking to a throttle valve of fuel in low throttle opening and proper distribution of the fuel to both intake passages in high throttle opening, in a conventional slide valve type throttle body of a fuel injection device for a spark ignition internal combustion engine used for an intake system having a primary intake passage and a secondary intake passage.

A means is adopted for using a bottom surface of the throttle valve as a deflector, by installing an injector in a body part opposed to the bottom surface of the throttle valve. In the low throttle opening, the fuel collides with the throttle valve bottom surface, and changes the direction, and is quickly carried to the downstream side without delay by suction air flowing at a high speed on the periphery. In the high throttle opening, the fuel is injected in the predetermined direction, and is distributed at a proper rate to the primary intake passage and the secondary intake passage.