[Problem] To develop a device that uses light to accurately measure the amount of temporal increase/decrease and the amount of change over time of a substance which changes temporally, and that displays the results thereof. [Solution] The present invention irradiates a sample including a substance to be measured with light from at least two light sources, and measures fluctuations relative to components other than the substance to be measured with light from at least one light source and measures fluctuations of the substance to be measured with light for measuring the substance to be measured. In order to accurately measure the amount of change of the substance to be measured, the fluctuation amount of the components other than the substance to be measured is set as a correction value. Measurement is conducted three times at certain intervals therebetween, and the difference between the first measurement value and the third measurement value is calculated, a temporal differential value of the difference between the first and second measurement values is computed, and a final result is found using the difference value between the first and third measurement values and the temporal differential value between the first and second measurement values.La présente invention vise à mettre au point un dispositif qui utilise la lumière pour mesurer avec précision la quantité d'augmentation/diminution temporelle et la quantité de changement au cours du temps d'une substance qui change temporellement, et qui affiche les résultats de cette mesure. À cet effet, la présente invention irradie un échantillon comprenant une substance à mesurer avec une lumière provenant d'au moins deux sources de lumière, et mesure des fluctuations par rapport à des constituants autres que la substance à mesurer avec une lumière provenant d'au moins une source de lumière et mesure des fluctuations de la substance à mesurer avec une lumière pour mesurer la substance à mesurer. De façon à mesurer avec
