We present a case of a man in his 60s who had been in clinical remission of ulcerative colitis (UC) after treatment with 5ASA. Over the clinical course, he developed an isolated deep ulcer at the end of the ileum. There were moderate active UC findings in the rectum. We diagnosed a simple ulcer associated with UC and started treatment with azathioprine and infliximab (IFX). Shortly after the treatment, the ulcer began to scar. We report a rare case of a simple ulcer that accompanied UC, and for which IFX was effective.