PROBLEM TO BE SOLVED: To provide a subject information acquisition device that allows highly reliable diagnosis.SOLUTION: The subject information acquisition device includes: retainer plate 101 (101a, 101b) to be a compression plate for compressing a subject radiation means 104 for radiating light acoustic wave detection means 105 for receiving an acoustic wave generated inside the subject and outputting an electric signal and control means 128 for displaying an acoustic wave image and pressure information on display means.SELECTED DRAWING: Figure 1