A display control device comprises an image acquiring unit which acquires observation image data, an image recording unit which records recorded image data, an image synthesizing unit which generates synthesized image data based on the observation image data and the recorded image data, a first selector, a second selector, and a selector interlock controller. The first selector outputs one of the observation image data and the synthesized image data to a first display device as first selected data. The second selector outputs one of the first selected data and the recorded image data to a second display device as second selected data. The selector interlock controller interlocks and controls the first selector 122 and the second selector 124.