A therapeutic agent containing Vasohibin for diabetic nephropathy, and a therapeutic agent containing Vasohibin for peritoneal sclerosis. Since the therapeutic agent containing Vasohibin of the present invention is a substance in which Vasohibin inhibits angiogenesis in an autocrine manner, the therapeutic agent is effective for inhibiting the progression of diabetic nephropathy and peritoneal sclerosis in which the inhibition in the angiogenesis or the production of cytokine is important, so that the therapeutic agent is suitably used in, for example, the treatment of a disease requiring an action for inhibiting the progression of diabetic nephropathy, and a disease requiring an inhibitory action for peritoneal sclerosis, or the like.