A light source apparatus includes a polarization conversion element, a fluorescent substance and a light source element. The polarization conversion element has a p/s-polarizing beam splitter film to separate polarization components of incident light into p-polarization component and s-polarization component. The fluorescent substance emits visible light as the incident light that is incident on the p/s-polarizing beam splitter film, which visible light is generated by that the fluorescent substance is excited by excitation light, and has a wavelength of longer wavelength region than a wavelength of the excitation light. The light source element emits a laser beam having a predetermined wavelength as the excitation light to irradiate the fluorescent substance with the excitation light so that a laser beam having a polarization plane between the polarization plane of p-polarized light and the polarization plane of s-polarized light exiting from the fluorescent substance is emitted as the incident light.