The present invention provides an agent for inhibiting alveolar airspace enlargement containing adiponectin or an agent for inhibiting alveolar wall destruction containing adiponectin. The pulmonary disease therapeutic agents of the present invention are highly safe drugs that possess an excellent effect of decreasing the deterioration of the pulmonary function, such as airflow limitation, and exhibit an extremely high effect of treating pulmonary disease accompanied by irreversible deterioration in pulmonary function, with fewer adverse side effects such as nausea, vomiting and gastric acid secretion.
