A light source unit according to an embodiment has a first light source which emits light in a first wavelength range, a second light source which emits light in a second wavelength range which differs from the light in the first wavelength range, a dichroic mirror to which the light in the first wavelength range and the light in the second wavelength range are incident from directions which differ from each other and which reflects or transmits the light in the first wavelength range and the light in the second wavelength range, and an optical device which is disposed on an optical path between the dichroic mirror and the second light source, and the optical device is a spectral member to which a coating is applied which transmits the light in the second wavelength range and reflects or absorbs the light in the first wavelength range.