The present invention relates to fuel injection device characterized by comprising a main body having an axial cylindrical bore, a fuel supply port, a plurality of fuel metering ports, and a plurality of fuel distributing ports communicating with said fuel metering ports; a rotor having an inlet port communicating with said fuel supply port in said main body, a single metering port associated with said metering ports in said main body, and a hole communicating with said two ports; means for driving said rotor for rotation in synchronism with the rotation of an engine; control means for axially sliding said rotor in unique association with the amount of suction air; and fuel supply means for supplying fuel to the fuel supply port in the main body through a pressure regulating valve, the arrangement being such that the length of time for communication between each metering port of the main body and the metering port of the rotor is controlled in connection with the r.p.m. of the engine and the amount of suction air, while the operation (total amount of suction air)/(engine r.p.m.) and the metering and distribution of fuel are performed.