A photoacoustic apparatus includes a processing unit configured to obtain: a first image data group generated based on acoustic waves generated by irradiating an object with light having a first wavelength a plurality of times； obtain position shift information associated with the irradiation timings of the light having the first wavelength on the basis of the first image data group, the obtained information providing first position shift information； second image data group generated based on acoustic waves generated by irradiating the object with light having a second wavelength different from the first wavelength a plurality of times； position shift information associated with the irradiation timings of the light having the second wavelength on the basis of the second image data group, the obtained information providing second position shift information； and obtain third position shift information on the basis of the first position shift information and the second position shift information.
