An LED illumination source is disclosed. The illumination source includes a metal base substrate including a line pattern and an insulating layer including a composite material with an inorganic filler and a resin composition. LED bare chips are mounted on one surface of the metal base substrate An optical reflector with holes to surround the bare chips is provided on the surface of the metal base substrate on which the LED bare chips are mounted. Stress relaxing means is provided between the metal base substrate and the optical reflector.