PROBLEM TO BE SOLVED: To provide a blood storage tank hardly causing liquid stagnation even with a change in the kind, injection speed, method, or the like of a medical solution to be injected when injecting the medical solution in a cardiotomy part of the blood storage tank.SOLUTION: The blood storage tank includes, in a housing, the cardiotomy part connected through a conduit tube. A blood passage through which blood flows, and a medical solution passage through which the medical solution flows, are formed in the conduit tube independently of each other. In a vertical direction, the lower end of a blood conduit tube part forming the blood passage is located on the lower side of the lower end of a medical solution conduit tube part forming the medical solution passage. The horizontal cross section of the medical solution conduit tube part is gradually reduced downward, and an opening surface of the lower end of the medical solution conduit tube part is formed larger than the horizontal cross section of the blood conduit tube part of the corresponding part.
