Be able to utilize regardless of the adult, the child and the newborn baby, adjusts to the size of the finger and adjusts the measurement cavity and it offers the pulse oxy meter which makes satisfactory measurement possible. The measurement cavity putting 110 accepting the suffering region (for example the finger) of the subject and the measurement cavity 110, it has the filling up component 140 which was formed with the material which transmits the light ray which it utilizes in measurement the luminous section to the measurement mechanism in addition 120 which has 121 to oppose and light absorbent section 122 and frame 130, for pulse oxy meter 100. As for filling up component 140 curvature of the curved surface of internal side is large in comparison with the curvature of the curved surface of the external side which has curved, it is something which curvature of the curved surface of the internal space of the measurement cavity conversion is obtained, it buries the opening of the finger and the internal space of the measurement cavity 110 by inserting filling up component 140 into measurement cavity 110, in order for the finger not to play in the measurement cavity 110 internal space, keep it can close.大人、小児、新生児を問わず利用でき、指の大きさに合わせて測定キャビティを調整し良好な測定を可能とするパルスオキシメータを提供する。パルスオキシメータ100には、被験者の被験部位(例えば指)を受け入れる測定キャビティ110と、測定キャビティ110を挟んで対向し合う発光部121と受光部122を備えた測定機構120と、筐体130に加え、測定に利用する光線を透過する素材で形成された充填部材140を備えている。充填部材140は湾曲している外面側の曲面の曲率に比べて内面側の曲面の曲率の方が大きく、測定キャビティの内部空間の曲面の曲率を変換せしめるものであり、充填部材140を測定キャビティ110内に入れることにより、指と測定キャビティ110の内部空間との隙間を埋め、指が測定キャビティ110内部空間で遊ばないように挟持せしめることができる。
