The present invention relates to a separation system and a separation material for easily and rapidly separating a red blood cell-rich fraction, a white blood cell-rich fraction, and/or a platelet-rich fraction from a biological fluid containing these blood cell components without the necessity of performing centrifugation. The separation of a red blood cell-rich fraction, a white blood cell-rich fraction, and/or a platelet-rich fraction from a biological fluid can be accomplished by capturing white blood cells and platelets on a blood cell separation material by contacting the biological fluid with the blood cell separation material, thereby providing a red blood cell-rich fraction; and recovering a white blood cell-rich fraction by separating white blood cells captured from the resulting blood cell separation material using a separation solution.