A fuel injection control device includes a basic-injection-use map for deriving a basic injection amount and an additional-injection-use map for deriving an additional injection amount, each corresponding to the throttle opening. During operation of the engine, in each engine cycle, a first calculation stage for calculating the basic injection amount, and a second calculation stage provided after the first calculation stage are set. A first injection amount and a second injection amount obtained by applying the throttle opening measured in the first calculation stage and the second calculation stage, respectively, are compared. When the second injection amount is greater than the first injection amount, an additional injection amount is calculated by subtracting the first injection amount from the second injection amount; and when the first injection amount is greater than the second injection amount, the basic injection amount calculated in the first calculation stage is corrected.