A method is disclosed for producing an artificial lung including a plurality of porous hollow fiber membranes for gas exchange which have an outer surface, an inner surface forming a lumen, and an opening portion communicating the outer surface with the inner surface. The method includes bringing any of the outer surface and the inner surface into contact with a colloidal solution that contains an antithrombotic high-molecular compound to circulate carbon dioxide gas to a side of the other surface. According to the present disclosure, an artificial lung can be produced in which a coating amount of antithrombotic high-polymer material (an antithrombotic high-molecular compound) on a hollow fiber membrane is increased.
