PROBLEM TO BE SOLVED: To provide an endoscope apparatus which can be easily inserted to the object to be observed by surely protruding an endoscope to be bent at a bendable part through an opening part of an overtube.SOLUTION: The endoscope apparatus 1 includes: an electrode E having the bendable part Ea at a tip part an overtube 2 which is inserted in the electrode E and assists insertion of the electrode E into the body and an opening part 4 opening on a sidewall at the tip part of the overtube 2. The apparatus is provided with: a first balloon 5 which is provided at a part adjacent to an opening part 4 on a part of an outer peripheral surface of the overtube 2 on the tip side of the opening part 4 in the longitudinal direction of the overtube 2, can be swollen and be contracted in an opening direction of the opening part 4 and a second balloon 6 which is provided at a part adjacent to the opening part 4 being a part of the outer periphery surface of the overtube 2 on a proximal end side of the opening part 4 in the longitudinal direction of the overtube 2, can be swollen and be contracted in the opening direction of the opening part 4.
