A biological signal measuring system includes: a light emitter emitting light beams having different N kinds of wavelengths, where N is an integer of four or more； a light receiver, a processor and an outputting section outputting (N-1) identified concentrations. Light attenuations A 1 , A 2 , A 3 ,...,A n are acquired based on changes of the received light intensities due to pressing of a living tissue at each of the N different wavelengths. The concentrations of the N-1 different components are obtained from differences of light attenuation at different wavelengths, namely A 2 -A 1 , A 3 -A 1 , etc.
