PURPOSE: To eliminate unnecessary fuel supply thus to improve fuel consumption, in a system where accelerated fuel is fed to carburetor upon decision of acceleration, by providing means for stopping decision of acceleration for predetermined time after setting of accelerated fuel supply.

CONSTITUTION: It is comprised of an opening sensor for detecting the opening of throttle valve 2 in carburetor and means 4 for detecting the magnitude of engine load. Exceeding of the variation of load per unit time detected through load detecting means 4 over specific level is decided to be acceleration through acceleration deciding means 31. Upon decision of acceleration, fuel supply setting means 32 will set the accelerated fuel supply to produce an accelerated fuel supply instruction from supply instruction means 33 to accelerated fuel supply means 1 on the basis of the setting fuel supply. Here, decision stop means 34 will stop decision of acceleration through acceleration deciding means 31 for predetermined time after setting of accelerated fuel supply.