A photobiological measuring device has a computing unit generating an unwanted component removal observation signal by removing the signal corresponding to the unwanted component from an observation signal. The computing unit is provided with: a mixing matrix making unit for separating observation signals into the products of a mixing matrix and independent component signals through independent component analysis a POWER spectrum computing unit generating transformed independent component signals, which are functions of frequency and intensity, by Fourier transforming the independent component signals, which are functions of time and intensity and computing POWER spectra in predetermined frequency bands of transformed independent component signals and an unwanted component signal determining unit detecting the independent component signal corresponding to the unwanted component from among the independent component signals by comparing the POWER spectrum in a predetermined frequency band of each transformed independent component signal with a threshold.
