An oil pump, comprising a rotor (3) performing a pump action for sucking oil in a suction passage (24) from suction ports (27) and feeding the oil to a delivery passage through delivery ports (19) according to the rotation thereof and an oil control valve for returning excess oil as a return flow to the suction passage (24) through a bypass passage (29) when the flow of the oil in the delivery passage (28) is excessively high, wherein an erosion resistant member (9) having an erosion resistance is installed on the inner wall surface of at least one of the suction passage (24) and the bypass passage (29) at a position opposed to the return flow of the oil, and the erosion resistant member (9) is formed in a discontinuous shape (for example, V-shape or U-shape) around a centerline (P1) in a cross section orthogonal to the centerline (P1).