To reduce sliding resistance of an outer gear of a trochoidal gear type fuel pump, and to reduce noise of the pump by delivery pressure pulsation.

Two inner gears 25 and 26 are eccentrically arranged on the inner peripheral side of the outer gear 24 by sandwiching a partition wall 28, and the eccentric directions of both inner gears 25 and 26 are mutually dislocated to the opposite side by 180° so that fuel pressure loads mutually act on the opposite side by 180° to the outer gear 24 from the two inner gears 25 and 26. The tooth number of the outer gear 24 is set to a minimum value '5' of the tooth number of an odd number, the tooth number of the inner gears 25 and 26 is set to a minimum value '4' of the tooth number of an even number so that a rotational phase of the two inner gears 25 and 26 is made different by a half pitch, a phase of a delivery pressure pulsing wave is made different by a half period of the pulsing wave, pressure pulsation is attenuated by interference, a generating frequency area of pump noise is reduced up to a generating frequency area of an engine sound, and the pump noise is masked with the familiar engine sound of a driver.