To acquire stable concentration information by a simple technique during photoacoustic measurement.SOLUTION: A subject information acquisition apparatus comprises: a signal acquisition unit for acquiring a first signal corresponding to first light and a second signal corresponding to second light, the first signal and the second signal being output by a probe which receives photoacoustic waves generated from a substance within a subject projected with the first light emitted from a light emission unit and having a first wavelength and with the second light having a second wavelength different from the first wavelength； a light amount ratio distribution acquisition unit for acquiring a light amount ratio distribution indicating a light amount ratio between the first light and the second light on a projection plane which is projected with light emitted from the light emission unit； and a concentration information acquisition unit for acquiring three-dimensional concentration information of the substance within the subject, using the light amount ratio distribution, the first signal, and the second signal. The concentration information acquisition unit assigns, as a light amount ratio at a first position within the subject, a value obtained based on a light amount ratio at a second position within the projection plane corresponding to the first position.SELECTED DRAWING: Figure 1【課題】光音響測定において、簡易な手法で安定した濃度情報を取得する。【解決手段】光出射部から出射された第１の波長を持つ第１の光と第１の波長と異なる第２の波長を持つ第２の光が照射された被検体内部の物質から発生する光音響波を探触子が受信して出力される、第１の光に対応する第１の信号と、第２の光に対応する第２の信号と、を取得する信号取得部と、光出射部から出射された光が照射される照射面における、第１の光と第２の光の光量比を示す光量比分布を取得する光量比分布取得部と、光量比分布と、第１の信号および第２の信号を用いて、被検体内部における物質の三次元の濃度情報を取得する濃度情報取得部を備え、濃度情報取得部は、被検体内部の第１の位置における光量比として、照射面内において第１の位置に対応する位置である第２の位置における光量比に基づく値を割り当てる被検体情報取得装置。【選択図】図１
