We investigated the effect of Onpi-to (TJ-8117) on the mesangial injury induced by anti-Thy-1 antibody. TJ-8117 (400 mg/kg/day, p.o.) given from the 1st day (from the day of injection of the anti-thymocyte serum) or 4th day (after mesangial proliferation), markedly inhibited the mesangial proliferation and hypercellularity in glomeruli. TJ-8117 prevented the increase in the number of PCNA or ED-1 positive cells in glomeruli. These results suggest that TJ-8117 is effective against glomerular disease with mesangial injury.