Anti-CD81 antibody displays not only a remission induction effect, but also a long-term remission maintenance effect on inflammatory bowel disease when administered in a single dose, and is therefore effective as a drug for maintaining remission from inflammatory bowel disease. Moreover, anti-CD81 antibody is effective as a drug for the prevention, amelioration and treatment of inflammatory bowel disease because it has preventive, therapeutic and ameliorating effects on refractory inflammatory bowel disease.
