A light source apparatus includes: an excitation light source including a laser light source; a first wheel that is controlled to rotate, and includes, in a part of a surface thereof to be illuminated by excitation light emitted from the excitation light source, a phosphor layer to be excited by the excitation light; a dichroic mirror that guides fluorescence emitted from the phosphor layer of the first wheel and the excitation light to an illumination optical system; and a second wheel that is controlled to rotate, and includes a dichroic filter that transmits light having a desired wavelength component of each of the fluorescence and the excitation light output from the dichroic mirror.