An annealing apparatus includes heating sources provided to face a wafer W, the heating sources having LEDs emitting lights to the wafer; light-transmitting members for transmitting the lights emitted from the LEDs; and cooling members made of aluminum and provided to directly contact with the heating sources, respectively. The heating sources include a plurality of LED arrays having supporters made of AlN, each having one surface on which the LEDs are adhered by using a silver paste; and other surface on which thermal diffusion members made of copper are adhered by using a solder. The LED arrays are fixed to the cooling member by using screws via a silicone grease.