An object of the present invention is to provide a brain function measuring device and a brain function measuring method that can eliminate or minimize calibration work. In order to solve this problem, a first light irradiation probe S1 for irradiating the subject's brain with light and a first light irradiation probe S1 are arranged adjacent to the first light irradiation probe S1 and are irradiated from the first light irradiation probe S1. First light detection probe D1 for detecting the light reflected by the brain of the light, and the second light that is arranged adjacent to the first light detection probe D1 and irradiates the brain of the subject with light. Irradiation probe S2, a second light detection probe D2 which is arranged adjacent to the second light irradiation probe S2 and detects the light reflected by the brain among the light irradiated from the second light irradiation probe S2. , And the amount of light measured for the channel between the first light detection probe D1 and the second light irradiation probe S2, per channel between the first light detection probe S1 and the first light detection probe D1. The amount of light emitted by the second light irradiation probe S2 is adjusted so that the observed value is obtained, and measurement is performed for the channel between the second light irradiation probe S2 and the second light detection probe D2. Provided is a brain function measuring device including a control unit 3 that adjusts the amount of light detected by the second light detection probe D2 so that the amount of light becomes the above-mentioned observed value.較正作業を不要にし、若しくは最小限に留めることのできる脳機能計測装置と脳機能計測方法を提供することを課題とする。 本課題を解決するため、被検体の脳に光を照射する第一の光照射プローブＳ１と、第一の光照射プローブS1に隣接して配設され、第一の光照射プローブS1から照射された光のうち脳で反射された光を検出する第一の光検出プローブD1と、第一の光検出プローブD1に隣接して配設され、被検体の脳に光を照射する第二の光照射プローブS2と、第二の光照射プローブS2に隣接して配設され、第二の光照射プローブS2から照射された光のうち脳で反射された光を検出する第二の光検出プローブD2と、第一の光検出プローブD1と第二の光照射プローブS2との間のチャンネルにつき計測される光量が、第一の光照射プローブS1と第一の光検出プローブD1との間のチャンネルにつき観測
