PROBLEM TO BE SOLVED: To provide: an ultraviolet light emitting device which is simple and compact, and capable of easily stabilizing a light emitting output of ultraviolet light a fluid concentration measurement device a dialyzer and an ozone concentration measurement device.SOLUTION: An ultraviolet light emitting device includes: a substrate 1 having a first main surface 10 and a second main surface 11 facing the first main surface 10 a light emitting part 2 disposed on the first main surface 10 of the substrate 1 and emitting ultraviolet light having a wavelength of 10 nm or more and 400 nm or less and a light receiving part 3 disposed, on the first main surface 10 of the substrate 1, at a position different from that of the light emitting part 2. A part of ultraviolet light emitted by the light emitting part 2 transmits through the inside of the substrate 1 to be emitted from the second main surface 11 to the outside, while the other part of the ultraviolet light emitted by the light emitting part 2 transmits through the inside of the substrate 1, is reflected on the second main surface 11, and enters the light receiving part 3. The light receiving part 3 subjects received ultraviolet light to photoelectric conversion to output an electric signal.COPYRIGHT: (C)2015,JPO&INPIT【課題】簡易且つ小型で、紫外光の発光出力を容易に安定化することができる紫外光発光装置、流体濃度測定装置、透析装置及びオゾン濃度測定装置を提供する。【解決手段】第1主面10と、該第1主面10と対向する第2主面11とを有する基板1と、基板1の第1主面10上に配置されて、波長が10nm以上、400nm以下の紫外光を発光する発光部2と、基板1の第1主面10上であって、発光部2とは異なる位置に配置された受光部3とを備え、発光部2が発光する紫外光の一部は、基板1の内部を透過し第2主面11から外部へ出射し、発光部2が発光する紫外光の他の一部は、基板1の内部を透過し第2主面11で反射して受光部3に入射し、受光部3は、受光した紫外光を光電変換して電気信号を出力する。【選択図】図1
