The present disclosure is directed to providing an apparatus and a method for suitably displaying a photoacoustic image for assisting diagnosis using an ultrasound image when restricting the degradation of diagnostic capability. An information processing method according to the present disclosure includes displaying an ultrasound image through transmission and reception of an ultrasonic wave to/from a subject, setting a partial region of the ultrasound image as a region of interest when the ultrasound image is being displayed, setting a light irradiation condition including a light quantity and a repetition frequency of irradiation light to the subject according to the region of interest, and receiving a photoacoustic wave generated through light irradiation to the subject under the light irradiation condition, and displaying a photoacoustic image of a region corresponding to the region of interest.
