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]-phen oxy]-7-methoxy-N-methyl-6-quinolinecarboxamide or a salt thereof, as an active ingredient.Se proveen un agente terapéutico y una composición farmacéutica que exhiben excelente efecto profiláctico o terapéutico contra la fibrosis o los síntomas asociados con la fibrosis； este agente terapéutico para la fibrosis contiene 4-[ 2-fluoro-4-[[[(2- fenilacetil)amino]tioxometil]amino]-fenoxi]-7-metoxi-N-metil-6-qu inolincarboxamida o una sal de la misma como un ingrediente activo.
