PROBLEM TO BE SOLVED: To solve the problem that a discharge lamp for use in a weatherometer performing a bright-dark cycle test, in which extinction and lighting of a light source have been conventionally repeated during transition between a lighting test and a dark test, needs to be applied with a high voltage when being lit and has the lifetime reduced by application of excessive load to an electrode due to discharge with the high voltage.SOLUTION: In a weatherometer, a light-shielding cover isolating a sample and a discharge lamp from each other during a dark test and an auxiliary cover integrated with the light-shielding cover are provided around the discharge lamp.
