Disclosed are a subject information acquisition device and subject information acquisition method whereby, in photoacoustic imaging, optical property values can be acquired accurately. The subject information acquisition device is provided with signal processing means comprising: a setting section that sets prescribed sensitivity regions corresponding to a plurality of respective acoustic wave detection elements, based on the sensitivity distribution of the plurality of acoustic wave detection elements an initial acoustic pressure acquisition section in which acoustic wave detection elements are acquired in which the region of interest is not included in the prescribed sensitivity region and that acquires the initial acoustic pressure in the region of interest without employing a detection signal corresponding to the region of interest an optical amount acquisition section that acquires an integrated optical amount in the region of interest, based on the detection signal for which the initial acoustic acquisition section was employed and an optical property value acquisition section that acquires an optical property value in this region of interest, using the initial acoustic pressure acquired by the initial acoustic pressure acquisition section and the integrated optical amount acquired by the optical amount acquisition section.Linvention concerne un dispositif dacquisition dinformations sur un sujet et un procédé dacquisition dinformations sur un sujet au moyen duquel, dans une imagerie photoacoustique, des valeurs de propriétés optiques peuvent être acquises avec précision. Le dispositif dacquisition dinformations sur un sujet est équipé de moyens de traitement de signaux comprenant : une section de réglage qui règle des régions de sensibilité prescrite correspondant à une pluralité déléments respectifs de détection dondes acoustiques, basée sur la distribution de la sensibilité de la pluralité déléments de détection dondes acoustiques une section dacquisition d
