A 59-year-old man was admitted to our hospital because of watery diarrhea and bloody stool lasting for a month. The patient had been a habitual smoker, smoking 25 cigarettes/day for 35 years. However, he had recently stopped smoking since a giant bulla in the left lung had been found. One month after discontinuing smoking, the patient's symptoms appeared. Colonoscopic examination demonstrated granulated mucosa, edema, and diminished vascular pattern were over the entire colon. Endoscopic and histological findings were compatible with the diagnosis of ulcerative colitis. We reported a case of ulcerative colitis that developed after smoking cessation and discussed the relationship between smoking and ulcerative colitis. Smoking may be associated with ulcerative colitis developed in middle aged person.