An endoscope includes an image sensor that is disposed at a front end portion of an insertion portion of the endoscope; a circuit board that is mounted with the image sensor; a plurality of electric wires that are electrically connected to the circuit board; and a retention member that has a retention portion tying up the electric wires; and the retention portion is disposed in a narrowed section that is provided in the insertion portion and inside a part adjacent to the front end portion in an axial direction of the insertion portion and narrowed in a narrowing direction perpendicular to the axial direction so that the electric wires are tied up to be longer in a direction perpendicular to the narrowing direction and the axial direction than in the narrowing direction.