A fuel supply system includes a low pressure fuel pump, which suctions and discharges fuel accumulated in a fuel tank, and a high pressure fuel pump, which suctions and discharges the fuel discharged from the low pressure fuel pump and supplies the fuel to a fuel injection valve installed in an internal combustion engine, the low pressure fuel pump, high pressure fuel pump, and fuel injection valve being connected in series, wherein the low pressure fuel pump and high pressure fuel pump are configured in such a way as to be driven or stopped independently of each other, one by each motor, and the pressure of the fuel discharged from the high pressure fuel pump is made variable by a combination of the drive or stop of the low pressure fuel pump and the drive or stop of the high pressure fuel pump.