A light source apparatus comprising: a plurality of light sources each having a light emitting area; an optical characteristic converter for each light source including a wavelength conversion element or an angular conversion element and configured to convert incident lights from the respective light source into emitting lights each having a wavelength or a diffusion angle different from that of incident light from the light source; a collimator lens provided for each light source and configured to collimate a divergent light emitted from the light source, and a first optical system for each light source configured to irradiate the incident light from the respective light source on the respective optical characteristic converter, wherein the first optical system is configured to convert a shape of the collimated light from the respective collimator lens into a shape non-similar to that of the light emitting area and to irradiate the shape-converted collimated lights as the incident lights to an irradiated area on the respective optical characteristic converter, the irradiated area corresponding to a respective light source, wherein the first optical system includes: a fly-eye lens which the collimated light from the collimator lens enters and which divides the collimated light into a plurality of light beams, and a condenser lens which superimpose the plurality of light beams on one another and which irradiate the superimposed light beams as incident lights on the irradiated area on the optical characteristic conversion element, and wherein the condenser lens corresponds to a respective light source of the plurality of light sources. a plurality of light sources each having a light emitting area; an optical characteristic converter for each light source including a wavelength conversion element or an angular conversion element and configured to convert incident lights from the respective light source into emitting lights each having a wavelength or a diffusion angle different from that of incident light from the light source; a collimator lens provided for each light source and configured to collimate a divergent light emitted from the light source, and a first optical system for each light source configured to irradiate the incident light from the respective light source on the respective optical characteristic converter, wherein the first optical system is configured to convert a shape of the collimated light from the respective collimator lens into a shape non-similar to that of the light emitting area and to irradiate the shape-converted collimated lights as the incident lights to an irradiated area on the respective optical characteristic converter, the irradiated area corresponding to a respective light source, wherein the first optical system includes: a fly-eye lens which the collimated light from the collimator lens enters and which divides the collimated light into a plurality of light beams, and a condenser lens which superimpose the plurality of light beams on one another and which irradiate the superimposed light beams as incident lights on the irradiated area on the optical characteristic conversion element, and wherein the condenser lens corresponds to a respective light source of the plurality of light sources. a fly-eye lens which the collimated light from the collimator lens enters and which divides the collimated light into a plurality of light beams, and a condenser lens which superimpose the plurality of light beams on one another and which irradiate the superimposed light beams as incident lights on the irradiated area on the optical characteristic conversion element, and wherein the condenser lens corresponds to a respective light source of the plurality of light sources.