PURPOSE: To disperse stress applied to the barrel part of a rotor, by constituting plural axially directed partition parts provided to the inner wall of the rotor for a centrifugal purifier by a curved surface having specific radius of curvature.

CONSTITUTION: To the barrel part 12 of a rotor, partition parts 13 formed by drawing a circular arc having radius of curvature (r) centering around O1WO4 are provided. This partition part 13 becomes thin in the wall thickness thereof in a symmetric form toward the circumference of a circle from the protruded part thereof as an apex and comes to the thinnest wall thickness (t') at the apex of a circular arc (l). By forming a plurality of thus constituted partition parts 13 toward the circumference of the circle of the inner wall of the barrel part 12 of the rotor, the cross areas at the bass parts of the partition parts 13 can be remarkably increased compared to that of a conventional one and the dispersion of load due to centrifugal effect can be attained as well as, because the partition parts 13 can be integrally formed with the barrel part of the rotor, mechanical strength can be increased.