To provide a centrifugal pump having improved pump efficiency and suction properties whereof the impeller has both a main plate and a side plate or only the main plate by restricting leak quantity from impeller liner parts.

In this centrifugal pump whereof the impeller 2 has both the main plate 2b and the side plate 2d or only the main plate 2b, a fixed side inner circumferential surface and a rotational side outer circumferential surface of the liner parts 2c, 2e as leak restriction parts of the impeller 2 are constituted of throttle mechanisms 4a, 4b that can contact with each other.