PURPOSE: To enable the use of a blood bag with an MAP liquid which is recently developed and has begun to be used by improving the bucket of the rotor for the centrifugal separator for sepn. of blood components to be used at the time of preparing blood pharmaceuticals for transfusion.

CONSTITUTION: The elliptic bucket 3 of the rotor 1 to be mounted to the centrifugal separator 6 for centrifugal sepn. of the blood in a blood bag and the cup to be put into the elliptic bucket are so formed that the internal shapes thereof are elliptic.