A fuel supply system in which a fuel filter has a large filtration area is obtained without increasing an outer diameter of the fuel supply system and an outer diameter of a tank hole through which a pump module is inserted in a fuel tank. The fuel supply system comprises a fuel pump 5, a fuel pressure regulator 9 for regulating pressure of fuel, and a fuel filter 6 having a hollow cylindrical filter case 7for filtering the fuel, and in which the filter case 7 has a holding hole 7a for holding the fuel pump, a center line CL1 of the holding hole is eccentric with respect to a center line CL2 of the filter case 7 by a predetermined distance M, and a first enlarged space portion S1 in which fuel system parts such as fuel pressure regulator 9 are accommodated is formed at a part surrounded by an outer circumferential portion of the fuel pump 5 and an outer circumferential portion of the filter case 7.