There is provided a medical observation device including: a microscope unit that includes an image sensor and images an operative site； and a holding unit that holds the microscope unit on a front end side. The holding unit includes a first rotation axis unit that supports the microscope unit to allow rotation about a first rotation axis substantially aligned with an optical axis of the microscope unit. From the microscope unit, a cable group including at least a signal cable that transmits a signal related to the image sensor and a light guide that guides illuminating light for imaging is run towards an outside through an interior of a housing of the first rotation axis unit.
