A fuel system for an excavator comprising: a fuel tank including a fuel supply line along which fuel is discharged therefrom and a return line along which the remaining fuel is returned thereto after being combusted on an engine; a water separator including a hand pump installed on a downstream side of the fuel tank in such a manner as to be connected to the fuel supply line and configured to remove water contained in the intake fuel and, and a first filter connected to the hand pump and configured to filter foreign substances in the fuel; an injection pump installed on a downstream side of the water separator and configured to supply the fuel, from which the foreign substances are filtered while passing through the first filter and a second filter connected to the first filter, to an injector at high pressure so as to inject the filtered fuel into an engine combustion chamber; a fuel control unit connected to the second filter and the injection pump and configured to control the amount of fuel that is supplied to the injector through the control of the injection pump; a check valve installed on the return line and configured to allow the remaining fuel that is remained after being used on the engine to remain on the injector side rather than being returned to the fuel tank along the return line in the case where the equipment is not operated by the start-off of the engine; and a pressure sensor installed in a pipe between the second filter and the fuel control unit and configured to detect the pressure of the fuel that has passed through the second filter and to output a detection signal for application to the fuel control unit. a fuel tank including a fuel supply line along which fuel is discharged therefrom and a return line along which the remaining fuel is returned thereto after being combusted on an engine; a water separator including a hand pump installed on a downstream side of the fuel tank in such a manner as to be connected to the fuel supply line and configured to remove water contained in the intake fuel and, and a first filter connected to the hand pump and configured to filter foreign substances in the fuel; an injection pump installed on a downstream side of the water separator and configured to supply the fuel, from which the foreign substances are filtered while passing through the first filter and a second filter connected to the first filter, to an injector at high pressure so as to inject the filtered fuel into an engine combustion chamber; a fuel control unit connected to the second filter and the injection pump and configured to control the amount of fuel that is supplied to the injector through the control of the injection pump; a check valve installed on the return line and configured to allow the remaining fuel that is remained after being used on the engine to remain on the injector side rather than being returned to the fuel tank along the return line in the case where the equipment is not operated by the start-off of the engine; and a pressure sensor installed in a pipe between the second filter and the fuel control unit and configured to detect the pressure of the fuel that has passed through the second filter and to output a detection signal for application to the fuel control unit.