Disclosed herein is a method for processing a physiological signal to measure physiological characteristics of a living organism. The method includes: (a) dividing P1′(t), which is obtained by differentiating one signal function P1(t) between two signal functions having different wavelength bands and representing the physiological characteristics of the living organism, by P2′(t) obtained by differentiating the other signal function P2(t) and (b) obtaining a constant b of the following function n1(t) and a cycle of the following function s1(t) through Math Formula 1:(P1′(t)/P2′(t))t=t1,t2,t3, . . . =k, (where P1(t)=s1(t)+n1(t), P2(t)=s2(t)+n2(t), as1(t)=s2(t), bn1(t)=n2(t), a, b and k are constants, t is time, and n1(t) and n2(t) are signal functions due to noise when measuring the physiological signal).
