PROBLEM TO BE SOLVED: To provide a stereoscopic imaging optical system that has a compact and simple configuration and photographs right and left images with an arbitrary angle of convergence, and an endoscope including the stereoscopic imaging optical system.SOLUTION: An stereoscopic imaging optical system includes: a front lens group Gf having a single optical axis Lc a back lens group Gb located on an opposite side relative to the front lens group, and having a single optical axis Lc arranged coaxially with that of the front lens group Gf and a deflection unit 2 arranged at a position including an image forming surface Im forming an image once between the front lens group Gf and the back lens group Gb, and deflecting light beams.
