A light source unit includes: a housing; a semiconductor laser that is disposed in the housing and that radiates excitation light; a first condenser optical system that condenses the excitation light; a dichroic mirror that selectively reflects the excitation light; a second condenser optical system that condenses the excitation light; a wavelength conversion member that performs wavelength conversion of the excitation light and emits wavelength-converted light; an emission section that outputs the wavelength-converted light transmitted through the second condenser optical system and the dichroic mirror; and a light blocking section that is disposed between an inner surface of the housing, the inner surface being in a traveling direction of the excitation light toward a reflection surface of the dichroic mirror, and a back surface, the back surface being an opposite side of the reflection surface, or is disposed on the inner surface of the housing.