The present invention provides a fuel supply device, which makes a fuel pump and a cover component unitized, thereby omitting a necessary shell case in the prior art. The fuel supply device (10) comprises a mounting plate (12) for closing an opening (70) formed on a fuel box (68), the fuel pump (14) arranged on the mounting plate (12), and a fuel filter (16) for filtering a fuel sucked by the fuel pump (14), wherein the fuel supply device (10) is used for supplying the fuel in the fuel box (68) outside the box. The mounting plate (12) is combined with the fuel filter (16) by a quick assembly component in a way that the mounting plate (12) is embedded with the fuel pump (14) and the fuel pump (14) is prevented from falling off by the fuel filter (16).