A fuel injection control device of a saddle-ride type vehicle, including a throttle opening detector that detects a throttle opening changing in conjunction with operation of a rider, a crank pulsar rotor that is provided around a crankshaft and has detection-target teeth disposed at equal intervals and a toothless part, a pulse generator that generates a crank pulse according to a passage state of the detection-target teeth, an engine rotational speed detector that detects the crank pulse to detect a rotational speed of an engine, a fuel injector that injects a fuel into an intake path of the engine, a basic injection amount calculator that calculates a basic injection amount (FICAL) based on the engine rotational speed and the throttle opening, an additional injection amount calculator that superimposes an additional injection amount on the basic injection amount based on a change amount (ΔTH) of the throttle opening, and a calculation timing decider that decides calculation timing of the basic injection amount (FICAL) based on the engine rotational speed and the throttle opening, the fuel injection control device comprising: a throttle opening read timing setter that sets timing at which the throttle opening is read, wherein the throttle opening read timing setter is so configured as to be triggered to detect the throttle opening used for calculation of the basic injection amount by start of the calculation timing of the basic injection amount (FICAL) if the calculation timing of the basic injection amount (FICAL) is at a position corresponding to the toothless part, and the throttle opening read timing setter detects the throttle opening based on crank pulse interrupt according to the crank pulse if the calculation timing of the basic injection amount (FICAL) is at a position other than the position corresponding to the toothless part; a stage assignor is provided and is arranged for dividing one rotation of the crankshaft into thirteen segments based on the output timing of the crank pulse and assigning stages to respective phases of the crankshaft, and in that the execution timing of the basic injection amount calculation (FICAL) is adjusted to earlier or later timing in a range of several stages depending on the engine rotational speed and the throttle opening; characterized in that if the engine has at least two cylinders, the throttle opening read timing setter is triggered to detect the throttle opening by start of the calculation timing of the basic injection amount (FICAL) for the cylinder in which the calculation timing of the basic injection amount (FICAL) is at a position corresponding to the toothless part, and detects the throttle opening based on crank pulse interrupt according to the crank pulse for the cylinder in which the calculation timing of the basic injection amount (FICAL) is at a position other than the position corresponding to the toothless part. a throttle opening read timing setter that sets timing at which the throttle opening is read, wherein the throttle opening read timing setter is so configured as to be triggered to detect the throttle opening used for calculation of the basic injection amount by start of the calculation timing of the basic injection amount (FICAL) if the calculation timing of the basic injection amount (FICAL) is at a position corresponding to the toothless part, and the throttle opening read timing setter detects the throttle opening based on crank pulse interrupt according to the crank pulse if the calculation timing of the basic injection amount (FICAL) is at a position other than the position corresponding to the toothless part; a stage assignor is provided and is arranged for dividing one rotation of the crankshaft into thirteen segments based on the output timing of the crank pulse and assigning stages to respective phases of the crankshaft, and in that the execution timing of the basic injection amount calculation (FICAL) is adjusted to earlier or later timing in a range of several stages depending on the engine rotational speed and the throttle opening; characterized in that if the engine has at least two cylinders, the throttle opening read timing setter is triggered to detect the throttle opening by start of the calculation timing of the basic injection amount (FICAL) for the cylinder in which the calculation timing of the basic injection amount (FICAL) is at a position corresponding to the toothless part, and detects the throttle opening based on crank pulse interrupt according to the crank pulse for the cylinder in which the calculation timing of the basic injection amount (FICAL) is at a position other than the position corresponding to the toothless part.