A system for supplying fuel to an internal combustion engine, while improving the utilization rate of an evaporation fuel, is provided. The raw fuel F0 is separated to a first fuel F1 and a second fuel F2 by a separation device 20. The evaporation fuel V derived from the first fuel F1 is suctioned from a condenser 30 by an operation of a vacuum pump 36, and then supplied to a first fuel tank 40. During this operation, at least a part of the evaporation fuel V transits its phase from a gas phase to a liquid phase and stored in the first fuel tank 40 as the first fuel F1.