A light source device according to the present disclosure includes a light emitting section configured to emit first light in a first wavelength band, a wavelength conversion layer configured to convert a part of the first light into second light in a second wavelength band, and a polarization split element configured to reflect third light having the first wavelength band and a first polarization direction, transmit fourth light having the first wavelength band and a second polarization direction, reflect fifth light having the second wavelength band and the first polarization direction, and transmit sixth light having the second wavelength band and the second polarization direction. Light intensity of the fourth light is controlled by controlling light intensity of light having the first polarization direction out of the first light entering the wavelength conversion layer and light intensity of light having the second polarization direction.