The forceps plug for an endoscope is mounted on a metal opening communicating with an insertion channel formed in an endoscope. The forceps plug for an endoscope includes a main body portion and a plurality of cap portions. The main body portion includes a mounting portion mounted on the metal opening and formed at one end thereof, and a cap mounting portion that protrudes in a cylindrical shape and is formed at the other end thereof. A closing film having a slit normally closed is formed between the mounting portion and the cap mounting portion. The respective cap portions are connected to the main body portion by flexible strip-like portions, and are formed of insertion holes for inserting the treatment tool with different inner diameters one by one at the centers of the cap portions, and are attachable and detachable on the cap mounting portion in an alternative manner.
