There is disclosed an operation microscope in which an observing and displaying system of an operating instrument are selected, and an endoscope image for observing a dead angle of the microscope and a navigation image are selectively displayed in a microscope observation field, so that a tomographic image, three-dimensionally constructed image, and the like can be selectively displayed in a display screen in accordance with a treatment position displayed in a monitor or an observation position of the operation microscope.
