This invention provides a continuous blood filtration apparatus capable of filtering a plurality of blood samples continuous by using blood filter units to prepare plasma or serum samples in a short period, which comprises, a conveyor conveying a plurality of blood reservoirs each of which contains a blood sample and in which a suction nozzle of a blood filter unit has been put, a manifold connected to a suction line, couples of a valve and a connector for connecting the manifold to the blood filter unit provided on the end of each branch of the manifold, and a mechanism of moving the blood reservoirs in vertical direction.