There is provided an endoscope system which can secure appropriate bending stiffness of an insertion portion while maintaining the slide length of an endoscope insertion portion. According to one aspect of one of the present invention, in an endoscope system including an endoscope and an insertion assisting tool in which the endoscope is inserted and which assists the insertion of an endoscope insertion portion into a body, a flexible portion of the endoscope insertion portion includes a projection region which projects from the distal end opening of a tube body when the endoscope insertion portion is located in the distal end position in a movable range with respect to the tube body of the insertion assisting tool, and the projection region includes a bending stiffness change portion in which bending stiffness increases from a first position on the distal end side to a second position on the proximal end side.
