PROBLEM TO BE SOLVED: To provide a concentration quantifying device reducing influence of noise by layers except an objective layer.SOLUTION: This concentration quantifying device includes: an irradiator 101； a first light receiving unit 102； a second light receiving unit 103； a first optical intensity acquiring unit 104； a second optical intensity acquiring unit 105； a first equivalent scattering coefficient calculator 106； an optical path length distribution storage unit 108； a time resolution waveform storage unit 109； an optical path length acquiring unit 110； an optical intensity model acquiring unit 111； an optical absorption coefficient calculator 112 calculating an optical absorption coefficient of an optional layer based on optical intensity acquired by the first optical intensity acquiring unit 104, the second optical intensity acquiring unit 105, or a third optical intensity acquiring unit, an optical path length of each layer of a plurality of layers of light scattering media acquired by the optical path length acquiring unit 110, and an optical intensity model acquired by the optical intensity model acquiring unit 111； and a concentration calculator 114 calculating the concentration of an objective component in the optional layer based on the optical absorption coefficient calculated by the optical absorption coefficient calculator 112.【課題】目的の層以外の層によるノイズの影響を軽減する濃度定量装置を提供する。【解決手段】照射手段１０１と、第１受光手段１０２と、第２受光手段１０３と、第１光強度取得手段１０４と、第２光強度取得手段１０５と、第１等価散乱係数算出手段１０６と、光路長分布記憶手段１０８と、時間分解波形記憶手段１０９と、光路長取得手段１１０と、光強度モデル取得手段１１１と、第１光強度取得手段１０４または第２光強度取得手段１０５、若しくは第３光強度取得手段が取得した光強度と、光路長取得手段１１０が取得した複数の光散乱媒質の層の各々の層の光路長と、光強度モデル取得手段１１１が取得した光強度モデルと、に基づいて、任意の層の光吸収係数を算出する光吸収係数算出手段１１２と、光吸収係数算出手段１１２が算出した光吸収係数に基づいて、任意の層における目的成分の濃度を算出する濃度算出手段１１４と、を含む。【選択図】図１
