To provide a heat treatment apparatus wherein the uniformity of the temperature distribution of a substrate can be surely and easily secured during heat treatment.

A region to be irradiated with light is divided into four zones: a ring zone RZ, an edge zone EZ, a middle zone MZ, and a center zone CZ. The power to be supplied to lamps for radiating light zone by zone, that is, radiating light only on an associated zone, in other words, a quantity of light for each lamp, is specified. The power to be supplied to the lamps which radiate light to the two adjacent zones, that is, a quantity of light for each of these lamps, is calculated based on a quantity of light specified for each lamp for radiating light only on the associated zone. Consequently, the mutual interference between these two zones due to the lamps which radiate light on these two zones can be suppressed, resulting in surely and easily ensuring the uniformity of the temperature distribution of the substrate W during heat treatment.