To enhance a lubricating function of a driven gear outer peripheral surface, and to enhance volume efficiency of a pump.

This internal gear pump device composed of a drive gear 1, a driven gear 2 composed of an internal gear part having a larger number of teeth than the driven gear 1 and a casing 3 for housing the drive gear 1 and the driven gear 2, is provided with a suction port 33 for supplying a hydraulic fluid in a volume chamber formed out of both gear parts 11 and 21, a discharge port 31 being formed of the volume chamber and discharging pressure oil, a first pocket 5 being arranged in a vicinal part of the discharge port 31 of the casing 3 and a place for contacting with an outer peripheral part of the driven gear 2 and introducing the pressure oil from the discharge port 31 and a second pocket 6 being arranged in a vicinal part of the suction port 33 and a place for contacting with the outer peripheral part of the driven gear 2 and introducing the hydraulic fluid form the suction port 33.