Abstract: A fuel delivery device for a fuel tank comprising a float chamber for sucking fuel in a normal state, a sub chamber for sucking a small quantity of fuel remaining within a tank and a communication chamber for communicating the float chamber and the sub chamber to each other in lower portions thereof En the fuel delivery device for a fuel tank, a sub float chamber is provided above the sub chamber, the sub float chamber has a gas discharge port communicating with-the fuel tank in an upper portion, a vent hole communicating with the sub chamber in a lower portion and a sub float valve within, and the sub float valve ascends and descends in accordance with a quantity of an excess fuel returned to the sub float chamber from the engine so as to open and close the vent hole.