An impeller for fuel pumps of automobiles, which maximizes the amount of fuel discharge of the fuel pumps by controlling the fuel inlet angle and the fuel outlet angle of the blades of the impeller, thus providing high operational pressures of the fuel pumps and improving operational performances of the fuel pumps, is disclosed. The impeller has a disc-shaped body, with a plurality of blades each having an inclined surface and provided around an outer edge of the disc-shaped body while being spaced out at regular intervals, and a plurality of impeller chambers defined between the blades while being vertically formed through the disc-shaped body to allow fuel to flow into and out of the chambers due to a high-speed rotating force of the impeller. The impeller further includes an inlet guide surface provided on each of the blades within a fuel inlet region of each of the impeller chambers, with a first angle defined between a vertical plane of the impeller and the inlet guide surface. The impeller further includes an outlet guide surface provided on each of the blades within a fuel outlet region of each of the impeller chambers, with a second angle defined between the vertical plane of the impeller and the outlet guide surface to be less than the first angle.