Abstract: A fuel injecting apparatus for injecting an amount of fuel into an engine is comprised of a housing, a nozzle connected to the housing and extending into the engine, a driving device disposed in the housing, a valve member fitted slidably in the nozzle, terminated outside the nozzle so as to be opposed thereto, and operated to open and close the nozzle when the driving device is turned on and turned off, respectively, a pressure chamber defined within the housing so as to be opposed to the lower side of the driving device, a first fuel chamber formed within the housing to which fuel is being supplied continually, a second fuel chamber formed between the housing and the nozzle, a measuring device disposed between the first fuel chamber and the second fuel chamber for determining the amount of fuel to be injected, a plunger disposed slidably between the pressure chamber and the first fuel chamber for establishing and interrupting the fluid communication between the first fuel chamber and the second fuel chamber