PROBLEM TO BE SOLVED: To provide a concentration determination apparatus, a concentration determination method and a program by means of which the adhesion state of an irradiation part and an observation object can be accurately measured and confirmed, thereby concentration of a target component in an optional layer can be non-invasively and accurately determined.SOLUTION: The concentration determination apparatus 100 includes: an irradiation part 106； a light receiving part 107； an optical path length distribution storage part 103； an optical path length acquisition part 108； a time resolution waveform storage part 105； an adhesion determination part 111 for determining whether or not the irradiation part 106 and the observation object are in the adhesion state； a measurement light intensity acquisition part 113 for acquiring the intensity of light received by the light receiving part 107 when the adhesion determination part 111 determines that the irradiation part 106 and the observation object are in the adhesion state； an absorption coefficient calculation part 117 for calculating the absorption coefficient of the target component of the optional layer； and a concentration calculation part 120 for calculating the concentration of the target component of the optional layer on the basis of the absorption coefficient acquired by the absorption coefficient calculation part 117.【課題】照射部と観測対象との密着状態を、精度良く測定し、確認することで、任意の層における目的成分の濃度を、非侵襲的にかつ精度良く定量することができる濃度定量装置及び濃度定量方法並びにプログラムを提供する。【解決手段】本発明の濃度定量装置100は、照射部106と、受光部107と、光路長分布記憶部103と、光路長取得部108と、時間分解波形記憶部105と、照射部106と観測対象とが密着状態であるか否かを判定する密着判定部111と、密着判定部111が照射部106と観測対象とが密着状態であると判定した場合に、受光部107が受光した光の強度を取得する計測光強度取得部113と、任意の層の目的成分の吸収係数を算出する吸収係数算出部117と、吸収係数算出部117が取得した吸収係数に基づいて任意の層の目的成分の濃度を算出する濃度算出部120とを備えている。【選択図】図１
