This photoacoustic imager (100, 200, 300, 400, 500, 600, 700) includes a light source portion (11a, 411a, 411b, 511a, 611a), a detection portion (13), an amplification portion (22, 222, 322, 422, 702) and an imaging portion (23), and the amplification portion is so configured that an acoustic gain which is a gain of the amplification portion for amplifying a detection signal resulting from an acoustic wave is larger than an ultrasonic gain which is a gain of the amplification portion for amplifying a detection signal resulting from an ultrasonic wave.
