Provided is an annealing apparatus, which is free from a problem of reduced light energy efficiency resulted by the reduction of light emission amount due to a heat generation and capable of maintaining stable performance. The apparatus includes: a processing chamber 1 for accommodating a wafer W; heating sources 17a and 17b including LEDs 33 and facing the surface of the wafer W to irradiate light on the wafer W; light-transmitting members 18a and 18b arranged in alignment with the heating sources 17a and 17b to transmit the light emitted from the LEDs 33; cooling members 4a and 4b supporting the light-transmitting members 18a and 18b at opposite side to the processing chamber 1 to make direct contact with the heating sources 17a and 17b and made of a material of high thermal conductivity; and a cooling mechanism for cooling the cooling members 4a and 4b with a coolant.