A 57-year-old man presenting with severe ulcerative colitis (UC) complicated by disseminated intravascular coagulation (DIC) was referred to our hospital. Since it was difficult to improve DIC immediately with any medical treatment, total proctocolectomy, ileoanal canal anastomosis, and ileostomy were performed on the patient. Soon after the surgery, his platelet count and coagulability improved, and he recovered from DIC. Thus, when the cause of DIC is probably UC itself, and medical treatment has limited efficacy in improving the DIC, surgery should be performed as soon as possible to eliminate the cause of DIC, considering the general condition of the patient.