An example of the closed-type blood reservoir of the invention is furnished with an outer shell in which a space is formed within its interior, a flexible septum that is interposed between a blood storage chamber shell and a volume adjustment chamber shell and that divides the space into a blood storage chamber for storing blood and a volume adjustment chamber for storing volume adjustment liquid, a blood inlet port, a blood outlet port, and a blood storage chamber air discharge port that are provided in the blood storage chamber shell such that they are in communication with the blood storage chamber, and a volume adjustment liquid port that is provided in the volume adjustment chamber shell such that it is in communication with the volume adjustment chamber, for injecting and ejecting the volume adjustment liquid into and away from the volume adjustment chamber, wherein the blood inlet port and the blood outlet port each are provided tangentially to the inner surface of the blood storage chamber shell such that blood that flows into the blood storage chamber from the blood inlet port can swirl along the inner surface of the blood storage chamber shell, and wherein the closed-type blood reservoir has a first blood flow route, provided in the blood storage chamber, that is formed by an outward concavity of the inner surface of the blood storage chamber shell, and that is in communication with the blood outlet port and at least part of which is formed in the direction of extension of the blood outlet port.
