Abstract: In this body tissue filling material, platelet-rich plasma is mixed into granular ?-tricalcium phosphate. The platelet-rich plasma is produced by a method consisting of a step in which blood is housed in a first vessel, the inside of which has been sterilized, a step in which blood cells are separated from the blood by allowing centrifugal force to act on the first vessel in which the blood is housed, a step in which the liquid remaining after separating the blood cells is transferred to a second vessel aseptically connected to the first vessel, a step in which the connection between the first vessel and the second vessel is sealed, a step in which plasma is separated from this liquid by allowing centrifugal force to act on the second vessel that houses the liquid, and a step in which the remaining platelet-rich plasma from which plasma has been separated is transferred to a third vessel aseptically connected to the second vessel.