PURPOSE: To achieve a higher fading promotion property, by reflecting light not irradiating a sample with a circular reflector in addition to a direct light from a light source to keep the temperature of the sample within a specified range as well.

CONSTITUTION: A sample 5 receives a shaded part as shown by (a) of a direct light from an arc light 4 and lights A, B, and C reflected from a reflector 8 while likewise, a sample 5' receives a direct light from a the arc light 4 and lights D, E and F reflected from the reflector 8', which strengthens the radiation energy of the samples 5 and 5'. Increase in the radiation energy on the sample surface causes a rise in the sample temperature but it is necessary to keep the sample temperature within a specified range of standard value. To maintain the temperature, air 13 from a blower is made to pass over the surface of the samples 5 and 5' to deprive heat on the surface of the samples to effectively that the sample temperature will be kept within a standard temperature range. This achieves a higher fading promotion property.