The blood bag system (10), the 1st bag which stores the blood which contains the multiple components (12) with, the 2nd bag which stores the medium specific gravity component (14) with, the 3rd bag which stores the light relative density component (16) with, the light relative density component and the medium specific gravity component the 1st bag (12) from the 2nd bag (14) the 1st tube which is transported (18) with, the 1st bag (12) from the 3rd bag (16) the 2nd tube which is transported (20) with it has the light relative density component. Blood treatment manner, as the 1st bag (12), centrifugal process and the light relative density component which the blood which contains the multiple components in inside centrifugal separation are done are transported the 1st tube (18) through, the 1st bag (12) from the 3rd bag (16), includes with the partition stage which the 1st tube (18) through, the 1st bag (12) from the 2nd bag (14) transports the medium specific gravity component.血液バッグシステム(10)は、複数の成分を含有する血液を貯留する第1バッグ(12)と、中比重成分を貯留する第2バッグ(14)と、軽比重成分を貯留する第3バッグ(16)と、軽比重成分及び中比重成分を第1バッグ(12)から第2バッグ(14)に移送する第1チューブ(18)と、軽比重成分を第1バッグ(12)から第3バッグ(16)に移送する第2チューブ(20)とを備える。血液処理方法は、第1バッグ(12)内で複数の成分を含有する血液を遠心分離する遠心工程と、軽比重成分を第1チューブ(18)を介して第1バッグ(12)から第3バッグ(16)に移送するとともに、中比重成分を第1チューブ(18)を介して第1バッグ(12)から第2バッグ(14)に移送する分離工程とを含む。
