A light source apparatus including: a solid state light source that includes a pair of electrodes and emits light in response to power being supplied with from the electrodes; a liquid medium that removes heat that is generated in the solid state light source; and a mounting unit which is provided a flow path in an interior thereof in which the liquid medium flows, including: a base that defines the flow path; and a placement member which defines a remainder of the flow path and on which the solid state light source is mounted.