PROBLEM TO BE SOLVED: To provide a subject information acquisition device and a subject information acquisition method capable of acquiring an optical characteristic value in photoacoustic imaging with a high degree of precision.SOLUTION: A subject information acquisition device has a signal processing means including: a setting part 41 for setting a predetermined sensitivity area corresponding to each of a plurality of acoustic wave detection elements e1, e2, and e3 based on the sensitivity distribution of the plurality of acoustic wave detection elements e1, e2, and e3 an initial sound pressure acquisition part 42 for acquiring initial sound pressure in an area of interest without using a detection signal corresponding to the area of interest acquired by the acoustic wave detection elements e1, e2, and e3 in which the area of interest is not included in the predetermined sensitivity area a light amount value acquisition part 43 for acquiring an integrated light amount value in the area of interest based on the detection signal used by the initial sound pressure acquisition part 42 and an optical characteristic value acquisition part 44 for acquiring an optical characteristic value in the area of interest, using the initial sound pressure acquired by the initial sound pressure acquisition part 42 and the integrated light amount value acquired by the light amount value acquisition part 43.SELECTED DRAWING: Figure 1
