A measuring apparatus of absorption information of scattering medium, comprising a light source for generating pulsed light, a light incidence section for making the pulsed light incident to a scattering medium, a light receiving section for receiving the light having propagated inside the measured object, a signal detecting section for temporally cutting a portion out of a light signal obtained by the light receiving section to acquire a measurement signal corresponding to the cut-out signal, a first arithmetic section for performing a measurement for acquiring measurement signals respectively at plural different timings or the like and for deriving a time integration value and a mean optical pathlength for each of the plural measurement signals obtained, and a second arithmetic section for calculating a change amount of concentration of an absorptive constituent, based on a predetermined relation among plural time integration values, plural mean optical pathlengths, an absorption coefficient per unit concentration of the absorptive constituent, and the change amount of concentration of the absorptive constituent.
