To provide a medical observation system which does not easily lose sight of an observation object even a technician does not make a slight motion intentionally during an observation with a narrowed field of view such as a high-power observation.

The system comprises a 3-dimension imaging apparatus for imaging a subject, having a zoom lens 40 for changing zoom factors, a motor 44, and so on; and a supporting device including a plurality of movable sections enabling a 3-dimensional transfer operation of the 3-dimensional imaging apparatus, electromagnetic brakes 14 and 19 to fix and release the movement of the movable sections and so on. It also has a control device 11 having an encoder 45 to detect a zoom factor and controlling the electromagnetic brakes 14 and 19 to enable the operational capability of the plurality of movable sections to vary in accordance with detection values detected by the encoder 45.