A concentration measurement apparatus measures a temporal relative change amount (ΔcHb, ΔO2Hb) of either or both of total hemoglobin concentration and oxygenated hemoglobin concentration in the head that vary due to repetition of chest compression, and includes a light incidence section making measurement light incident on the head, a light detection section detecting the measurement light propagated through the interior of the head and generating a detection signal in accordance with the intensity of the measurement light, and a CPU determining, based on the detection signal, the relative change amount (ΔcHb, ΔO2Hb) and performing a filtering process of removing frequency components less than a predetermined frequency from frequency components contained in the relative change amount (ΔcHb, ΔO2Hb).
