To provide a motor-driven fuel pump, in which driving noise of a pump is reduced and the fuel discharge pressure is increased.

A casing 31 is provided with a conical recessed part 35, and a discharge hole 36 is bored in the upper base part 33. An impeller 10 includes a conical surface 11A, a lower end surface 13 and an upper end surface 13, wherein a passage recessed part 15 is recessed in the substantally central part of the lower end surface 13, and the lower end surface 13 is provided with a radial groove 16 directed from the passage recessed part 15 to the outer peripheral surface 10A and opened downward. The conical surface 11 above the radial groove 16 is provided with a spiral groove 17 directed from the lower side to the upper side. The casing 31, the impeller 10 and the cover 20 are sequentially disposed on the housing 1, and a pump chamber 40 is formed by a conical recessed part 35 and a blocking part 21. The impeller 10 is disposed in the pump chamber 40, connected to an output shaft 2 in such a manner as to be rotated synchronously and disposed in such a manner as to be moved in the direction X-X of the longitudinal shaft center of the output shaft 2. A spring 41 presses the impeller 10 to the side where the conical surface 11 of the impeller 10 comes very close to the conical surface 34.