Provided are a light source device that can effectively cool a surface side of a light-emitting element substrate, and a projection type display device that includes the same. The light source device includes substrate (290), light-emitting element (210), optical element (400), and optical element support member (300). Two through-holes (220) are formed in substrate (290). Light-emitting element (210) is mounted on substrate (290). Optical element support member (300) is located to surround two through-holes (220) and light-emitting element (210), and forms, with substrate (290), flow path (700) that passes through light exit surface (211) of light-emitting element (210). Each through-hole (220) and flow path (700) are connected to each other.