A stereoscopic observation system includes a stereoscopic optical unit and stereoscopic camera. The optical unit is provided with a pair of objectives for stereoscopic observation and optical devices corresponding to the respective objectives. The stereoscopic camera is connected to the stereoscopic optical unit and used to pick up optical images formed by the optical devices. At least one of the stereoscopic camera and the optical unit serves as an instrument to be supported. A support unit supports the instrument. A rotation mechanism is incorporated in the support unit, and has a rotary shaft substantially parallel to an optical axis of the objectives. The rotation mechanism supports the instrument such that the instrument can rotate about the axis of the rotary shaft.