We performed anesthesia for a subtotal gastrectomy in a 70-year-old female patient with paramyotonia congenita (PC). She had been diagnosed with PC at the age of 47 years by electromyogram analysis. Several points to consider have been revealed regarding the management of anesthesia in patients with PC. In this patient, anesthesia was safely maintained using sevoflurane and nitrous oxide together with concomitant epidural anesthesia using mepivacaine. Efforts should be made to prevent perioperative attacks of muscle weakness when planning anesthesia for patients with this kind of disorder. Specifically, refraining from the use of muscle relaxants, care with regard to the composition of infusion fluids during operations, and the maintenance of body temperature are required for anesthesia. In addition, postoperative pain management using a continuous epidural block proved to be a useful method.