A fuel supply system includes a fuel pump 2 and a housing 1 that are disposed within a fuel tank 6. A damping material 50 is disposed on an upper end portion of a sidewall of the housing 1. The damping material 50 reduces the transmission of vibrations generated by the fuel pump 2 from to the fuel tank 6 to thereby prevent the fuel tank from vibrating. The damping material 50 may include an elastic material having a specific gravity of 0.12 to 0.4. Alternatively, the damping material 50 may include a fuel-resistant paper material.