A laser scanning microscope includes an exciting observation light source, a stimulation light source, a first scanning portion that two-dimensionally scans the exciting observation light across a specimen, a second scanning portion that sets an incident position of the stimulation light on the specimen, an optical path combining portion that brings the exciting observation light and the stimulation light to an identical optical path, an objective lens that irradiates the specimen with the exciting observation light and/or the stimulation light while collecting fluorescence light emitted from the specimen, and a detecting portion that detects the collected fluorescence light, the optical path combining portion being disposed so as to be in an optically conjugate relationship with the first scanning portion and the second scanning portion.