An LED light source apparatus comprises a circular base having thermal conductivity, an insulative substrate concentric with the base and including a pass-through hole provided to pass through an upper surface and a lower surface of the substrate, at least one mounting area formed having a central portion of an upper surface of the base exposed from the pass-through hole of the substrate, and a plurality of LED elements mounted on the mounting area and electrically connected to electrodes provided on the upper surface of the substrate, the pass-through hole being formed in a circular shape concentric with the base and the substrate.