A blood component separation device comprising: a centrifugal separator configured to separate a predetermined blood component from blood; and a container for containing the predetermined blood component centrifugally separated, wherein the blood component separation device is configured to perform (a) centrifugal separation step for introducing whole blood drawn from a donor into the centrifugal separator to separate the whole blood into a plurality of blood components, (b) circulation flow step for introducing a predetermined first blood component, among centrifugally separated blood components, into the centrifugal separator together with whole blood, and (c) circulation/acceleration step, performed after a predetermined amount of the first blood component is separated in the circulation flow step, in which supply of whole blood to the centrifugal separator is stopped to introduce only the first blood component into the centrifugal separator to further circulate the first blood component for a predetermined period of time, and a circulation speed is then increased so that a second blood component is separated by the centrifugal separator to be collected, and whole blood collected from the donor is temporarily stored in a temporary storage container during at least a time period in the circulation/acceleration step characterized in that the circulation/acceleration step includes a first collecting step for transferring a low-concentration portion of the second blood component to the temporary storage container and a second collecting step for collecting a high-concentration portion of the second blood component, and the low-concentration second blood component transferred to the temporary storage container is introduced into the centrifugal separator together with whole blood collected in the temporary storage container in a following cycle and whole blood drawn in the following cycle. a centrifugal separator configured to separate a predetermined blood component from blood; and a container for containing the predetermined blood component centrifugally separated, wherein the blood component separation device is configured to perform (a) centrifugal separation step for introducing whole blood drawn from a donor into the centrifugal separator to separate the whole blood into a plurality of blood components, (b) circulation flow step for introducing a predetermined first blood component, among centrifugally separated blood components, into the centrifugal separator together with whole blood, and (c) circulation/acceleration step, performed after a predetermined amount of the first blood component is separated in the circulation flow step, in which supply of whole blood to the centrifugal separator is stopped to introduce only the first blood component into the centrifugal separator to further circulate the first blood component for a predetermined period of time, and a circulation speed is then increased so that a second blood component is separated by the centrifugal separator to be collected, and (a) centrifugal separation step for introducing whole blood drawn from a donor into the centrifugal separator to separate the whole blood into a plurality of blood components, (b) circulation flow step for introducing a predetermined first blood component, among centrifugally separated blood components, into the centrifugal separator together with whole blood, and (c) circulation/acceleration step, performed after a predetermined amount of the first blood component is separated in the circulation flow step, in which supply of whole blood to the centrifugal separator is stopped to introduce only the first blood component into the centrifugal separator to further circulate the first blood component for a predetermined period of time, and a circulation speed is then increased so that a second blood component is separated by the centrifugal separator to be collected, and whole blood collected from the donor is temporarily stored in a temporary storage container during at least a time period in the circulation/acceleration step characterized in that the circulation/acceleration step includes a first collecting step for transferring a low-concentration portion of the second blood component to the temporary storage container and a second collecting step for collecting a high-concentration portion of the second blood component, and the low-concentration second blood component transferred to the temporary storage container is introduced into the centrifugal separator together with whole blood collected in the temporary storage container in a following cycle and whole blood drawn in the following cycle.