Provided is an information processing method configured to further accurately calculate an absorption spectrum of blood based on light applied to a living body such as a human finger. The information processing method includes the steps of: irradiating a living body with near-infrared light having a plurality of wavelengths； measuring, based on the near-infrared light received from the living body, a pulsating signal corresponding to each of the plurality of wavelengths； performing a principal component analysis on multi-wavelength time-series data including the measured pulsating signal corresponding to each of the wavelengths so as to remove noise from the pulsating signal； and calculating an absorption spectrum based on a variation width of the pulsating signal that is removed noise.
