To provide a lamp annealing device which has a stable lamp annealing performance regardless of the deterioration of a lamp and the devitrification of a quartz window or the like, and also to provide a method of heating which permits the stable annealing of a semiconductor film formed on a transparent substrate using the lamp annealing device.

The lamp annealing device comprises a means for measuring the illuminance of the light radiated from a light source of the device or a means for measuring a current value when the lamp is lighted up by a predetermined power. The lamp annealing device is also provided with a means for evaluating the state of the device based on the measurement result of the means. Based on the evaluation result of the evaluating means, the lamp power and the distance between the lamp and the substrate are adjusted and then annealing is conducted, and so a stable annealing is available regardless of the deterioration of the lamp or the devitrification of quartz or the like.