We report a relatively rare cecum cancer revealed by the formation of a colocutaneous fistula after gastrectomy for gastric cancer. The patient was an 80-year-old man, who was examined at our hospital with chief complaints of epigastralgia, nausea, and vomiting. A close examination gave a diagnosis of gastric cancer, and a distal partial gastrectomy was performed. From the 11th day after surgery, discharge of pus was noted from the scar of an appendectomy performed 40 years before and a fistula formed in that region. In a fistulograph, the contrast medium flowed out into the ascending colon, suggesting a colocutaneous fistula. Under colonoscopy, illumination of the ileocecum region was insufficient because of deformation due to adhesion. In spite of conservative therapy, convalescence and recurrence were repeated. Finally, exudate from the fistula was diagnosed as pathologically malignant in the 5th postoperative month. Thus, with the diagnosis of ileocecal cancer, ileocecal resection and curettage of the fistula were performed. The postoperative course was uneventful, and the patient was discharged on the 23rd day after this last surgery. It is necessary to consider not only an inflammatory disease, but also the possibility of colon cancer, when one comes across a case with a colocutaneous fistula.