Provided is a pharmaceutical composition useful as a prophylactic and therapeutic agent for fibrosis, particularly pulmonary fibrosis. One embodiment of the present invention is: a pharmaceutical composition for preventing fibrosis, treating fibrosis and/or preventing the progression of fibrosis, which contains stanniocalcin 1(STC1) as an active ingredient; or a pharmaceutical composition for preventing pulmonary fibrosis, treating pulmonary fibrosis and/or preventing the progression of pulmonary fibrosis, which contains STC1 as an active ingredient.