A centrifuge microscope that includes: a rotary disk in which are provided a slit and a sample chamber; a light source for illumination; a projecting optical system; and an objective lens. The projecting optical system includes an imaging lens, a pair of reflecting mirrors, and a projecting lens which are constructed and arranged such that an erect image or an inverted image of the slit is projected on a sample contained in the sample chamber. During rotation of the rotary disk, the slit image and the sample sweep by each other in front of the objective lens, whereby the sample can be observed via the objective lens as a still image having better definition.