A light source unit including an excitation light source for emitting light in a blue wavelength band, a fluorescent wheel, a light emitting device for emitting light in a red wavelength band and a light guiding optical system for guiding light emitted from the fluorescent wheel and the light emitting device to a light guiding device. The fluorescent wheel has a fluorescent area where a green fluorescent material layer for emitting fluorescent light in a green wavelength band is disposed and a diffuse area for converting light emitted from the excitation light source into diffuse light of which directivity is weak are disposed end to end in a circumferential direction. A concentration of weight content of the green fluorescent material and a thickness thereof are such that a luminescent intensity of fluorescent light emitted from the green fluorescent material layer is enhanced.