To provide a microscope incorporating an automatic focus adjustment device that eliminates the need for a complicated operation in which the front focusing position of an objective lens is set to a desired observing position.

The microscope includes: a focus detecting optical system 7 for imaging a light image based on light from a light source 20 onto an object via an objective lens 12, and then imaging, via the objective lens, the reflected light of the light image from the object; a photoelectric converter 30 disposed in the imaging position of the focus detecting optical system and used for detecting the reflected image; an observing optical system imaging adjustment means 52 for adjusting the imaging position of the observing optical system 3 including the objective lens, based on a signal of the reflected image obtained by the photoelectric converter; a focus detection optical system imaging adjustment means 8 for adjusting the imaging position of the focus detecting optical system based on the signal of the reflected image obtained by the photoelectric converter; and a switching control means 41 for switching the signal from the photoelectric converter 30 to the observing optical system imaging adjustment means 52 or focus detection optical system imaging adjustment means 8.