To provide a self-priming pump improved in self-priming performance while keeping pumping performance.

This self-priming pump comprises an impeller chamber 33 communicated to a water sucking channel 43 and accommodating an impeller 44, a distribution channel 34 communicated to a discharge pipe 60 and mounted adjacent to the impeller chamber 33 through a wall part 35, a water supply port 36 formed on the wall part 35 for communicating the impeller chamber 33 and the distribution channel 34, and a stator 23 and a rotor 41 for rotating and driving the impeller 44. The water supply port 36 is provided with a rectifier plate 37 extended along the flowing direction of the water W flowing between the impeller chamber 33 and the distribution channel 34.