Provided are a therapeutic agent and a pharmaceutical composition which exhibit excellent prophylactic or therapeutic effects against fibrosis or symptoms associated with fibrosis. This therapeutic agent for fibrosis contains 4-[2-fluoro-4-[[[(2-phenylacetyl)amino]thioxomethyl]amino]-phenoxy]-7-methoxy-N-methyl-6-quinolinecarboxamide or a salt thereof, as an active ingredient.