1. An inverted microscope that allows observation of a specimen from underneath, the inverted microscope comprising: an objective lens holding unit that holds an objective lens configured to collect at least observation light from the specimen; a tube lens configured to focus the observation light collected by the objective lens; a branching unit configured to branch an optical path of the observation light from the tube lens; and an observation image switching device that is removably provided in a microscope main body between the objective lens and the tube lens and is configured to switch between wavelengths of an observation image or between magnifications of the observation image.