A pumping apparatus is adapted for providing a small amount of flow rate under high pressure and includes a pumping chamber, a rotating shaft and an impeller in the form of a disk which impeller is connected at its central portion to the rotating shaft to rotate in the pumping chamber. A first pumping section of the pumping apparatus comprises a bypass regenerative pump which includes grooves formed on the opposite side surfaces of the impeller and arranged in a circle surrounding the rotating shaft, and groove-like channels formed on the wall of the pumping chamber in facing relationship to the grooves on the impeller with narrow gaps therebetween. A second pumping section of the pumping apparatus is connected in series to the first pumping section between the outer peripheral portion of the impeller and the wall of the pumping chamber, and comprises a regenerative pump which includes grooves provided on the outer peripheral portion of the impeller.