We report a relatively rare case of cecal cancer with dermatomyositis. An 81-year-old man was diagnosed with dermatomyositis associated with the symptoms of eruption, limb muscle weakness, and difficulty swallowing. Colonoscopy revealed a type 2 tumor in the cecum. The patient underwent laparoscopic ileocecal resection. Although it was impossible for the patient to stand before the surgery, he could stand 10 days after the surgery and walk without assistance 14 days after the surgery. In addition, the eruption disappeared, and the preoperatively high creatine kinase(CK)value normalized. Dermatomyositis with malignant tumor has been reported to be associated with poor prognosis. Symptoms related to dermatomyositis may be improved by the resection of the associated tumor. Therefore, it is important to treat the malignant tumor when the patient's condition permits.