Provided is an artificial lung in which a filling amount of blood is effectively reduced and a function of the artificial lung can be favorably exhibited.An artificial lung 100 has a filling portion 110 communicating with an inlet port 101 and an outlet port 102 for blood and configured to be filled with blood, a heat exchange portion 160 including a bundle of a plurality of hollow fibers 163 for heat exchange and is provided inside the filling portion, a gas exchange portion 170 including a bundle of a plurality of hollow fibers 173 for gas exchange and disposed in the filling portion to be adjacent to the heat exchange portion, and a porous member 180 disposed in a gap 190 between the heat exchange portion and the gas exchange portion and filling the gap.
