Provided is an endoscope (1A) including an inserted portion (2) that is inserted into a body, an observation optical system (3) that is provided at a distal-end portion of the inserted portion (2) and that acquires an image of the heart, and a supporting expansion portion (4A) that makes the heart support the distal-end portion of the inserted portion (2) and that is provided with a basal-end-portion balloon (8), which is provided closer to a base-end portion than the distal-end portion of the inserted portion (2) is, and a distal-end-portion balloon (7), which is provided so as to overhang forward from the distal-end portion of the inserted portion (2), wherein the base-end-portion balloon (8) is disposed on the opposite side from the distal-end-portion balloon (7), with the inserted portion (2) interposed therebetween.