To provide a centrifugal pump capable of improving the maximum suction lift capability of the pump and obtaining high prime speed.

This centrifugal pump has a discharge duct 128 for changing flow of liquid into circular flow at an inlet of the discharge duct 128 and changing it into flow in the direction of tangential line at an outlet of the discharge duct in a volute to achieve the maximum self-priming and suction lift capability. As a result, the separation of air from discharged liquid to the maximum extent is realized to reduce quantity of air included in the discharged liquid recirculated into a recirculation inlet of the self-priming pump. This pump is well-suited for a trash pump.