An endoscopic treatment method includes: inserting an endoscope into a digestive tract; forming a damaged area in at least a portion of the digestive tract along a circumferential direction by performing cauterizing while keeping a mucosal layer by observing with the endoscope; and forming an incomplete stenosis in the digestive tract, while restoring the damaged area, wherein the damaged area is formed by causing damage to a mucosal base layer, the mucosal base layer having an interface that contacts a submucosal layer.