PURPOSE: To provide a stereoscopic viewing endoscope capable of obtaining a stereoscopic image by both of the naked eye and an image pickup element.

CONSTITUTION: The endoscope is provided with an insertion part 1 and an observation part 2, and an objective lens system 11 for forming the image of an object, a 1st relay lens system 12 for transmitting the image formed by the objective lens system 11 and a 2nd relay lens system 13 for forming an exit pupil are arranged in the insertion part 1. Two pupil dividing mirrors 20 and 21 as pupil dividing means and a pair of secondary optical systems 30a and 30b for receiving the divided luminous flux are arranged in the observation part 2. The secondary optical systems 30a and 30b are respectively constituted of mirrors 31a and 31b, image forming lens systems 32a and 32b, half mirrors 60a and 60b, image receiving elements 34a and 34b, condenser lenses 32c and 32d and eyepiece systems 33a and 33b.