A treatment instrument for an endoscope is provided that is suitable for cutting submucosa in endoscopic submucosal dissection. The treatment instrument for an endoscope includes a treatment portion having cutting means at a tip of an insertion portion that is to be inserted into the body. The main unit of the treatment portion is formed in a toothed-wheel shape which alternately has a peak portion and a valley portion where the cutting means is provided in the valley portions.
