PROBLEM TO BE SOLVED: To provide a blood oxygen addition device for improving gas exchange capacity.SOLUTION: The blood oxygen addition device 1 includes: an oxygen addition part 2 for performing gas exchange to add oxygen to blood and remove carbon dioxide in the blood and a housing 4 having a body part 5 formed in a tubular shape, which houses an oxygen addition part 2. A blood inflow part 21 for making the blood flow in from an outer peripheral side of the oxygen addition part 2 and a blood outflow part 22 located inner side of an inner peripheral surface of the body part 5, which makes the blood through the oxygen addition part 2 flow out are formed in the housing 4.
