The purpose of the present invention is to acquire a novel and efficacious anti-fibrosis agent. Use is made of an anti-fibrosis agent that comprises an integrin a8ß1 antagonist. Alternatively, use is made of an anti-fibrosis agent that comprises an anti-integrin a8ß1 antibody capable of specifically binding to at least one amino acid in a cap sub-domain of integrin a8 chain and the vicinity thereof. Alternatively, use is made of an anti-fibrosis agent that comprises an anti-integrin a8ß1 antibody capable of specifically binding to R120 of integrin a8 chain and the vicinity thereof, or S132 and the vicinity thereof. The aforesaid antagonist may be an anti-integrin a8ß1 antibody capable of binding to integrin a8ß1 of any origin, for example, human, mouse or rat.
