A stereoscopic-vision endoscope optical system includes a pair of objective optical systems, a pair of relay optical systems, and a pair of image forming optical systems. The image forming optical system includes a first lens unit, a first optical-path bending element, and a second optical-path bending element. The objective optical system and the relay optical system are disposed in a first optical path. A second optical path is formed between the first optical-path bending element and the second optical-path bending element. A third optical path is formed between the second optical-path bending element and a final image. The second optical path is positioned farther from the central axis, than the first optical path. The third optical path is positioned closer to the central axis, than the second optical path.
