There is provided a method of treating gastroesophageal reflux disease, which includes dissecting one of a mucosal layer and a submucosal layer of at least one of an esophagogastric junction and a stomach in a range less than an entire circumference of a circumferential direction so that moderate stenosis occurs due to cicatrization in an area in which one of the mucosal layer and the submucosal layer is dissected.