A 39-year-old man visited our hospital with lower leg pain and fever. We suspected sepsis because of an infectious disease. He was hospitalized, and treatment was initiated. After admission, we received information that mice were present in his living environment. Moreover, we considered leptospirosis in the differential diagnosis and started the administration of ceftriaxone and minocycline. On the 10th day after admission, after examination by the National Institute on Infectious Diseases, we diagnosed him with leptospirosis. The patient was transferred to the hospital for rehabilitation on day 23 after admission. It is important to consider leptospirosis even in non-epidemic area.