A centrifugal pump impeller 11 includes an impeller body in which an inner channel 35 is formed, and a single centrifugal vane 37 provided in the impeller body so as to have a leading edge at an outlet and a trailing edge at a predetermined point of an outer periphery of the impeller body. The centrifugal vane 37 is designed so that the area of an outer channel 36, which is defined by the centrifugal vane 37, in an angle range of 270° in a peripheral direction from the trailing edge of the centrifugal vane 37 to the total area of the impeller body surrounded by the outer periphery of the impeller body is less than 0.3.