A fuel supply device is disclosed. Through a simple structure, the fuel supply device is capable of realizing reduction of fuel suction pressure loss, restraint of steam suction, prevention of the phenomena that steam stays inside a pump, stable pump output, stability control over fuel pressure, and the like. In the fuel supply device, a pump part (20) is driven through an electric motor part (10), fuel pumped in the pump part (20) is pressurized and discharged. The pump part (20) comprises a housing (21) equipped with a suction connection head (23) and a discharge connection head (24), an oil cylinder (26) which is accommodated inside the housing and equipped with multiple pistons (25), a shaft (11) arranged at the electric motor part (10), an inclined plate (12) which enables reciprocating motion of the multiple pistons, multiple suction ports (26b) which serve as fuel passageways for guiding the fuel into a plenum chamber and a bush (28) which is roughly cylindrical-shaped, wherein the multiple suction ports (26b) run through the cylinder in an axial direction in such a way that the suction ports correspond to all pistons, two end parts of the bush are inserted and kept in the oil cylinder and the electric motor part, fuel pumped in through the suction connection head is guided to multiple suction ports, and the pistons (25) and the suction ports (26b) are disposed in different spaces (28c) which are separated from each other.