A light source unit includes a light emitting element supporter to support a plurality of light emitting elements disposed with a dispersed pattern in a two-dimensional direction as a light emitting element assembly, and light emitted from the light emitting element assembly exits to a target. The light emitting element supporter includes a ventilating hole at an inner portion of two dimensional direction of the light emitting element assembly, and cooling air, supplied from a rear side of a light emitting side of the light emitting element assembly, passes through the ventilating hole to the light emitting side of the light emitting element assembly.