An endoscope and a treatment tool are respectively inserted through an endoscope insertion passage and a treatment tool insertion passage of an overtube inserted into a body wall. A forward and backward movement operating part provided in a cable part provided to extend from a base end of an endoscope insertion part of the endoscope is arranged at a position adjacent to an operating part of the treatment tool. The forward and backward movement operating part includes a hook part having an opening, and a forward and backward movement operation of the endoscope can be performed by passing the index finger of a right hand gripping the treatment tool through the opening. Therefore, the forward and backward movement operation of the endoscope can be performed with the forward and backward movement operation of the treatment tool using only the one hand that operates the treatment tool.
