A light source apparatus including a first heat transfer element, a second heat transfer element, at least one first light emitting element, and at least one second light emitting element is provided. The first heat transfer element has a first carrying surface and a first heat dissipation surface opposite to the first carrying surface. The second heat transfer element surrounds the first heat transfer element and has a second carrying surface and a second heat dissipation surface opposite to the second carrying surface. The thermal resistance of the first heat transfer element is smaller than the thermal resistance of the second heat transfer element. The first and the second light emitting elements are disposed over the first and the second carrying surfaces respectively. The luminance of the first light emitting element is easier to vary with a change of temperature than the luminance of the second light emitting element.