Provided are: a device that is for separating/housing blood components and that can more easily and aseptically separate/house platelet rich plasma； and a method for preparing platelet rich plasma. The device (1) for separating/housing blood components is provided with: a blood storage section (2)； a component housing section (3) for housing a component that is part of blood； and a joining tube (4) that joins the blood storage section (2) and the component housing section (3). The blood storage section (2) has: a tube shaped blood storage vessel (21) that is flexible； a blood lead in pathway (27) that leads blood into the blood storage vessel (21)； and a component lead out pathway (28) that leads out a component that is part of blood from the blood storage vessel (21). The component housing section (3) has: a component lead in pathway (37) that leads in a component that is part of blood led out from the blood storage vessel (21)； and a metal needle (371) that extends from the component lead in pathway (37) towards the interior space of the component housing section (3) and can return the component that is part of blood housed in the component housing section (3) towards the blood storage vessel (21).
