An example of a blood storage tank of the closed type comprising: an outer shell forming an inner space a partition wall which is located between a blood storage chamber shell and a volume-regulating chamber shell and by which the above-described space is divided into a blood storage chamber for storing blood and a volume-regulating chamber for storing a liquid for regulating volume a blood in-flow port, a blood out-flow port and a blood storage chamber ventilation port which are provided in the blood storage chamber shell in such a manner as being connected to the blood storage chamber and a volume-regulating liquid port which is provided in the volume-regulating shell in such a manner as being connected to the volume-regulating chamber and by which a volume-regulating liquid is injected into the volume-regulating chamber and discharged therefrom wherein the blood in-flow port and the blood out-flow port are provided each in the direction tangential to the inner face of the blood storage chamber shell so that the blood flowing from the blood in-flow port into the blood storage chamber can circle over the inner face of the blood storage chamber shell, the blood storage tank of the closed type is formed by making an outward depression of the inner face of the blood storage chamber shell, and a first blood chamber, which is connected to the blood out-flow port and at least a part of which is formed along the extension direction of the blood out-flow port, is formed in the blood storage chamber.
