A drive unit 5 of a surgical microscope apparatus 1 moves an entire optical system horizontally. A driver 175 moves a head lens 13 vertically. An imaging device 56a detects reflected light (observation light) of illumination light guided by an observation optical system 30. A controller 60 obtains a cross-sectional shape of the observation light based on the result of the detection of the observation light by the imaging device 56a, and controls the drive unit 5 to move the optical system horizontally so that this cross-sectional shape becomes a specified reference cross-sectional shape. Moreover, the controller 60 obtains the luminance distribution of the observation light based on the result of the detection of the observation light by the imaging device 56a, and controls the driver 175 to move the head lens 13 vertically so that this luminance distribution becomes a specified reference distribution profile.
