Disclosed is an endoscope having an extra-fine diameter capable of improving strength and durability of outer and/or inner tube constituting an insertion portion of the endoscope while maintaining good insertion performance and operability, capable of easily and precisely locating lenses when various kinds of lenses are arranged. As such outer and/or inner tube constituting the insertion portion of the endoscope having an extra-fine diameter, a specific electrocast tube formed by a predetermined manufacturing method is used.
