The present invention is an endoscope system comprising an endoscope provided with a distal end inserted into a subject body and a proximal end having a site capable of being held by a physician and provided with an endoscope insertion unit having a first flexible portion arranged on the distal end thereof and a second flexible portion coupled to the proximal end of the first flexible portion and provided with a site having an outer diameter larger than a site having the maximum outer diameter of the first flexible portion and an endoscope insertion assisting device, in which the inner diameter of a distal opening of an insertion hole through which the endoscope insertion unit is inserted is substantially equal to the outer diameter of the second flexible portion.
