A photopretismography (PPG) device (100) for measuring physiological changes, which is combined with a light source that emits an optical signal having a variable intensity depending on skin characteristics by detecting the reflection of the optical signal. A first and second photodetector (130) that can operate to supply a current signal and a signal processing circuit that can operate to convert the current signal into a PPG signal to measure physiological changes. The device to be provided is disclosed. [Selection diagram] FIG. 17生理学的変化を測定するためのフォトプレチスモグラフィ（ＰＰＧ）装置（１００）であって、皮膚特性に依存して可変な強度を有する光信号を放出する光源と、光信号の反射を検出して結合電流信号を供給するように動作可能な第１および第２の光検出器（１３０）と、生理学的変化を測定するために電流信号をＰＰＧ信号に変換するように動作可能な信号処理回路とを備える装置が開示される。【選択図】図１７
