It is intended to provide a highly safe, orally administrable preventive and/or therapeutic agent for thrombosis and/or embolism that can be applied to a thrombosis and/or embolism patient with severe renal impairment. The present inventors have found that even for a thrombosis and/or embolism patient with severe renal impairment, use of edoxaban at a dose of 15 mg once a day can effectively prevent thrombosis and/or embolism while avoiding the risk of bleeding. The present inventors have also found that even for a thrombosis and/or embolism patient with severe renal impairment, edoxaban at a dose of 15 mg once a day can effectively prevent thrombosis and/or embolism with safety over a long period.