To provide a device capable of carrying out stable fuel supply around the whole rotating region concerning a fuel supply device of a supercharging engine.

A venturi part 103a having a fuel discharge port 110a is interposed on the middle of an intake air passage to communicate a supercharging means and a combustion chamber to each other, the fuel discharge port 110a and a float chamber 102 (fuel reservoir part) are communicated to each other by a fuel supply passage, and fuel is supplied to the venturi part 103a by differential pressure of pressure on the fuel reservoir part side and pressure on the side of the fuel discharge port. A part between the supercharging means and the venturi part 103a or a part in the downstream of the venturi part 103a and in the neighbourhood of the venturi part 103a and the inside of the fuel reservoir part 102 are communicated to each other by a pressure pipe (pressure passage) 126, the middle of the same pipe 126 is branched into first and second passages 126a, 126b, large and small throttle diameter throttle parts 130a, 130b are provided on each of the passages, a solenoid valve 131 (selection valve) is interposed in the first passage, and a CPU 132 to close the solenoid valve 131 at the time of a low rotational region is provided.