Peak specification unit 31 specifies, based on a plurality of photoacoustic-images according to detection signals of photoacoustic-waves detected in a plurality of postures, a photoacoustic-image with the strongest detection signal of a detected photoacoustic-wave among the plurality of photoacoustic-images in a peak search mode. Posture determination unit 32 determines whether or not the posture of the probe 11 at the time of detecting photoacoustic-waves of a generation source of the photoacoustic-image matches the posture of the probe 11 at the time of detecting photoacoustic-waves of a generation source of the photoacoustic-image specified by the peak specification unit in a normal mode. Display control unit 27 displays the photoacoustic image on a display screen, and in a case where the posture determination unit 32 determines that the postures match each other, displays a report indicating the postures matching each other on the display screen.