To provide a microscope apparatus in which both a visible-light image by ordinary observation light and a fluorescence image emitted from a body tissue by an indosyanine green derivative labeled antibody are observed simultaneously.

A sample 2 which is stained with an indocyanine green derivative labeled antibody is irradiated with beams of illumination light from lamps 41, 51 by which light in a first wavelength band containing at least a part of the excition wavelength of a fluorescent substance and light in a second wavelength band containing at least a part of visible light are radiated. Thereby, a light image which contains reflected light and infrared light is emitted from the sample 2. The light image is separated into a fluorescence (infrared light) component and a visible-light (reflected light) component by using a second dischroic mirror 70. A fluorescence image and a visible-light image which are imaged and obtained by a CCD 71 and a CCD 72 corresponding to the light image for the respective components are observed and diagnosed.