A 76-year-old man presented with many bullous lesions and erythema over his whole body in August 2014. Blood examination showed an elevation of the anti-BP180 antibody (658 U/mL) and a biopsied specimen of the skin lesions showed subepidermal bulla. A diagnosis of bullous pemphigoid was made based on the clinical and histological findings. Although 20 mg/day of prednisolone was administered, there was a poor response and consequently the dose of steroid was increased to 70 mg/day after 2 weeks. Bullous pemphigoid related to a malignant tumor was suspected. Colonic endoscopic examination revealed a sigmoid colon cancer and he underwent a sigmoidectomy with lymphodenectomy. The histopathological findings revealed a moderately-differentiated adenocarcinoma, pT1b, pN1, pStage Ⅲa, and he received adjuvant chemotherapy(UFT/ LV). The dermatological findings were rapidly relieved after tumor resection and anti-BP180 antibody was normalized. He has had no signs or symptoms of recurrence, both of the cancer and the bullous pemphigoid, for 9 months after the operation.