A photoacoustic apparatus is used which includes: a receiving element receiving acoustic wave from an object； a processor generating image data inside of the object； a changer changing irradiation positions of light on the object； and a wide-area image acquirer of the object, wherein the processor generates, for the irradiation positions, a local-area image of the object corresponding to the irradiation position, and based on a comparison between a plurality of local-area images obtained for the irradiation positions and a comparison between the plurality of local-area images and the wide-area image, integrates the plurality of local-area images.
