In a photoacoustic image generation apparatus including a photoacoustic image generation unit that generates a photoacoustic image based on a detection signal and a sound speed in a subject and a sound speed setting unit that sets the sound speed in the subject, the sound speed setting unit extracts a region having a predetermined range including a high signal value pixel collection portion having a region size larger than a reference region size as a tip region in a photoacoustic image generated based on an assumed sound speed and the detection signal and sets a sound speed of a photoacoustic image having a maximum image evaluation value as the sound speed in the subject among photoacoustic images for respective sound speeds generated by changing the sound speed in a predetermined sound speed range for the tip region.
