PURPOSE: To contrive to improve the laser performance by a method wherein the distribution of absorbing excited light within the cross-section of a laser rod is made uniform by enabling uniform irradiation over the whole laser rod with excited light.

CONSTITUTION: A flash lamp 2 which emits excited light and the laser rod 3 are arranged in a light-collecting cylinder 1. In this case, the flash lamp 2 and the laser rod 3 are arranged on the first focus 4 of the light-collecting cylinder 1 and on its second focus 5, respectively. The light-emitting cylinder 1 is made of a photo-permeable substance formed out of e.g. a glass pipe 6 arranged on the inner surface side and transmitting the excited light, an excited-light reflection substance 7 which reflects excited light in arrangemet on the outer surface side of this glass pipe 6, and a reflected-substance protection layer 8 arranged on the outer surface side of the substance 7. Therefore, the excited light radiated out of the flash lamp 2 can be collected by uniform irradiation over the whole laser rod 3, regardless conditions of luminous distribution of excited light within the cross-section of the flash lamp 2.