LIGHT IRRADIATION DEVICE AND LIGHT IRRADIATION THERAPY/PROPHYLAXIS DEVICE

PROBLEM TO BE SOLVED: To obtain a light irradiation device including a plurality of irradiation surfaces in a light emission part, and to provide a light irradiation therapy/prophylaxis device.SOLUTION: The light irradiation device 1 comprises a light emission unit 2 which emits light, a reflection unit 3 which reflects irradiation light from the light emission unit 2 and a light guide unit 4 which guides the reflected light from the reflection unit 3 to a subject to be irradiated. The light guide unit 4 comprises a first and second light guide face 12 and 18. The reflection unit 3 comprises a first reflection unit 16 which reflects a portion of radiation light to the first light guide face 12, a second reflection unit 19 which reflects incident light to the second light guide face 18, and a third reflection unit 20 which reflects a portion of the other radiation light to the second reflection unit 19 as the incident light. The third reflection unit 20 is arranged so as to incline to the light emission unit 2 and has a translucent units 27 wherein the closer the translucent unit is to the light emission unit 2, the greater the quantity of translucent of the radiation light.