A blood storage vessel (5) in its housing (30) is provided with a cardiotomy section (2). A conduit tube (90) provided in communication with an intracardiac blood inflow port (50) so as to effect inflow of the blood from the intracardiac blood inflow port into the cardiotomy section is inserted in the cardiotomy section from its upside downward. The conduit tube on its side face is provided with a slit (91) extending from the lower end of the conduit tube upward. Alternatively, the conduit tube may be provided with a through hole disposed on the side face of the conduit tube at a location close to the lower end thereof. Accordingly, even when the lower end of the conduit tube submerges in the blood within the cardiotomy section, there can be inhibited any increase of resistance of blood inflow to the cardiotomy section.
