A clear fluorescence image is obtained by preventing external light from mixing with weak fluorescence emitted from a specimen, while reducing the size of the overall apparatus. The invention provides a fluorescence microscope apparatus including a stage for mounting a specimen; an objective lens for collecting fluorescence from the specimen; a moving mechanism for relatively moving the stage and the objective lens; a first cover member secured to the objective lens; a second cover member, provided at the stage, for enclosing a tip of the objective lens and a space above the stage, together with the first cover member; and a light-blocking member allowing relative movement of the first and second cover members while preventing leakage of light from a gap between the two cover members.