A laser scan type fluorescence microscope includes a laser light source section, an objective optical system for condensing excitation light from the laser light source section on a sample, a scanning device to scan a surface of the sample with the excitation light from the laser light source section, a pupil projection lens arranged between the scanning device and the objective optical system, a detection optical system for detecting fluorescence that emanates from the sample and passes the objective optical system and the pupil projection lens. The objective optical system has an objective lens and an image forming lens for forming an intermediate image of the sample, and a back focal position of the objective lens is made conjugate with a position near the scanning device by the image forming lens and the pupil projection lens, wherein the following condition is satisfied: 0.15.ltoreq.D/L.ltoreq.0.5, where D is a parfocal distance of the objective lens, and L is a distance from the sample surface to the position conjugate with the back focal position of the objective lens and located near the scanning device.