PROBLEM TO BE SOLVED: To provide a technique improving safety and convenience of a treatment instrument for applying ultraviolet light.SOLUTION: A treatment instrument 10 for applying ultraviolet light to a skin, the treatment instrument 10 including: a cover member 20 disposed to cover over the skin such that a space 18 is formed between itself and the skin as an application object a light output part 32 outputting the ultraviolet light toward an inner surface 26 of the cover member 20 and a reflection member 40 provided inside the cover member 20 and reflecting the ultraviolet light to be output from the light output part 32 toward the skin as the application object.SELECTED DRAWING: Figure 2COPYRIGHT: (C)2018,JPO&INPIT【課題】紫外線を照射する治療器の安全性および利便性を高める技術を提供する。【解決手段】治療器10は、皮膚に紫外線を照射するための治療器10であって、照射対象の皮膚との間に空間18が設けられるようにして皮膚の上を覆うように配置されるカバー部材20と、カバー部材20の内面26に向けて紫外線を出力する光出力部32と、カバー部材20の内部に設けられ、光出力部32から出力される紫外線を照射対象となる皮膚に向けて反射させる反射部材40と、を備える。【選択図】図2