To provide an artificial lung with vein reservoir, allowing easy drawing-around, and allowing as short as possible the suppression of the lengths of respective tubes to be used, when connecting the tubes through which blood passes to a reservoir and an artificial lung and drawing around the tubes.

This artificial lung 1 with vein reservoir includes: the reservoir 2 temporarily storing the blood; the artificial lung 3 positioned on the downstream side of the reservoir 2, and performing gas exchange with the blood flowing down from the reservoir 2; and a connector 4 connecting the reservoir 2 and the artificial lung 3. The connector 4 is configured to be able to move the artificial lung 3 horizontally relatively to the reservoir 2 in a use state in which: the reservoir 2 is positioned above it; and the artificial lung 3 is positioned below the reservoir 2.