Disclosed is an annealing device that includes a processing chamber into which a wafer is received, a heating source having a plurality of light emitting diodes (LEDs) for emitting a light toward the wafer, which faces the surface of the wafer, and a light transmissive member provided corresponding to the heating source, into which the light from the light emitting elements is transmitted. The heating source has the light emitting elements attached on a support toward the wafer. Each of the light emitting elements is individually covered with a lens layer made of a transparent resin.