An optical property distribution, such as an absorption coefficient of the inside of a subject, is highly precisely acquired. A photoacoustic imaging apparatus includes an acoustic converting unit configured to receive acoustic waves generated by irradiating a subject with emitted light and to convert the acoustic wave to an electrical signal； and a processing unit configured to determine a light intensity distribution inside the subject on the basis of a light intensity distribution or an illuminance distribution of the light incident on the surface of the subject and to generate image data on the basis of the electrical signal and the determined light intensity distribution inside the subject.
