To provide an autofocus microscope capable of visualizing a focusing position on the sample surface with a simple constitution without adding a new light source for illuminating a mark indicating the focusing position on the sample surface and without changing the conventional optical system disposed in the microscope in the least.

In the autofocus microscope, a target member 40 which comprises: a translucency target plate 42 having a target 42a formed thereon; a target holding member 43 holding the target plate 42 so as to permit the transmission of illumination light and having a substantially truncated conical shape; a case body 41 movably holding the target holding member 43 with an energizing spring 44 and permitting the transmission of the illumination light to the target plate 42; and a pair of left and right adjustment screws 45, 46 penetrating the case body 41, being abutted on a tapered surface of the target holding member 43 and moving the same, is disposed on an illumination light path of the illumination optical system.