A projection system includes an excitation light source, an imaging unit, a control unit, a projecting unit, and a dichroic mirror. The excitation light source applies to a subject light of a predetermined wavelength band including excitation light. The imaging unit captures a fluorescent image resulting from fluorescence emission of the subject. The control unit generates image data for projection based on the fluorescent image captured by the imaging unit. The projecting unit projects a projection image based on the image data for projection onto the subject with visible light. The dichroic mirror transmits light of a wavelength band of fluorescence emitted by the object and reflects the visible light from the projecting unit. The dichroic mirror is disposed to match an optical axis of light incident on the imaging unit with an optical axis of light exiting from the projecting unit.
