An apparatus for fixing an instrument within the intestinal canal, according to the present invention, is a fixing apparatus for surrounding, from outside the intestinal canal, and fixing an instrument that is installed within the intestinal canal for protecting an anastomotic site after a resection surgery of a tube-type organ, characterized in that the apparatus for fixing an instrument within the intestinal canal has a band-shaped body having predetermined thickness and width, wherein the body is formed of a biodegradable (absorbent) material or a non-absorbent material, which does not react with foreign bodies in the human body, wherein the body has a low elongation rate in the length direction thereof, and wherein both edges of the body in the width direction thereof are processed soas to have a flexible form so that when the edges come in contact with an outer surface of the intestinal canal, injuries are not made to the outer surface of the intestinal canal. According to the present invention, the band-shaped fixing apparatus, which is for surrounding, from outside the intestinal canal, and fixing the instrument that is installed within the intestinal canal for protecting the anastomotic site after a resection surgery of a tube-type organ, has an elongation rate of less than 10%, and both edges of the band have flexible forms, wherein the instrument is fixed from outside the organ, and is fixed at a proper pressure, so as to maintain the wall shape of the organ, while not affecting the organ.