An endoscope system includes an endoscope including an insertion section formed in an elongated shape, a flexible tube portion provided at a proximal end side of the insertion section, and a rigidity changing mechanism portion provided inside the flexible tube portion, and configured to change rigidity of the flexible tube portion by an operation performed on a hand side, and a flexible overtube formed in a cylindrical shape extending in an axial direction, into which the insertion section is inserted, where a rigidity change region of the flexible tube portion by the rigidity changing mechanism portion is set to be from an intermediate portion to a proximal end portion of the flexible tube portion, and a total length of the overtube in the axial direction is set to be shorter than a total length of the rigidity change region.