To provide a light irradiation device for detecting damage of a housing to prohibit light irradiation.SOLUTION: A light irradiation device 100 applies light 200 to an object, and the irradiation device 100 comprises a light source 102, a housing 110 comprising an opening 101 for emitting the light 200 applied from the light source 102 to the outside, an optical sensor 103 arranged in the housing 110, and control means 104 for stopping emission of a predetermined amount of the light from the light source 102 if the optical sensor 103 detects outside light incident on the inside from the outside of the housing 110.SELECTED DRAWING: Figure 1【課題】筐体の破損を検出して光の照射を禁止する光照射装置の提供。【解決手段】光２００を対象物に照射する光照射装置１００であって、光源１０２と、光源１０２から照射される光２００を外部に出射させる開口１０１を有する筐体１１０と、筐体１１０内に配置される光センサ１０３と、筐体１１０外から内方に入射した外光を光センサ１０３が検出した場合、光源１０２の所定光量の光の出射を停止する制御手段１０４とを備える光照射装置１００。【選択図】図１
