An endoscope system includes: an endoscope 1 including an elongated insertion portion 12 provided with a bendable bending portion 16, the insertion portion being inserted into a duodenum 90 and a first balloon 10a to a fourth balloon 10d for moving a one-side surface 17k of a distal end portion 17 located nearer to a distal end side than the bending portion 16 in the insertion portion 12 in parallel with respect to a field of view direction S of an objective lens 34 which is a diameter direction of the insertion portion 12, separately from bending of the bending portion 16, the one-side surface being located in a circumferential direction along an insertion direction W of the insertion portion 12 and parallel to a central axis P of the insertion portion 12.
