A photoacoustic imager (100, 200, 300, 400) includes a light source portion (11), a detection portion (12, 26, 226), and an imaging portion (25, 225, 325, 425), and the imaging portion is configured to generate a photoacoustic wave image indicating a detection object in motion by acquiring difference data of signals acquired on the basis of a plurality of photoacoustic wave signals detected at different times of generated photoacoustic wave signals.
