[Objective]Light is prevented from being irradiated onto positions different from portions at which photoacoustic images are to be generated.[Constitution]An ultrasound driving means (23) causes ultrasonic waves to be transmitted from an ultrasonic wave detecting section (21) of a probe (11) as an example of acoustic waves. The ultrasonic wave detecting section (21) detects reflected acoustic signals of the transmitted ultrasonic waves. An image constructing means (26) generates an ultrasound image based on the reflected acoustic signals. A reference image storing means (28) has stored therein an ultrasound image obtained when the probe (11) is at a position suited for generating photoacoustic images as a reference image. A probe position judging means (29) compares the features of the ultrasound image and the features of the reference image. A laser control means (30) instructs a laser unit (13) to output light if it is judged that the features of the reflected acoustic signals match. The ultrasonic wave detecting section (21) detects photoacoustic signals generated within the subject due to irradiation of laser light. The image constructing means (26) generates a photoacoustic image based on the photoacoustic signals.
