1. A photoacoustic apparatus comprising: a light source configured to generate a plurality of lights, each of the plurality of lights having a different wavelength from each other; a converting element configured to receive photoacoustic waves generated in a subject by irradiating the subject with the plurality of lights; a first distribution obtaining unit configured to calculate a plurality of pieces of property distribution information, corresponding to the plurality of lights, which each represents an optical absorption coefficient distribution, an initial sound pressure distribution, or an optical energy absorption density distribution within the subject, the property distribution information being based on photoacoustic waves generated by irradiating the subject with each of the plurality of lights; a second distribution obtaining unit configured to calculate, a plurality of times, a plurality of pieces of at least part of oxygen saturation distribution information within the subject by performing at least one of coordinate shifting processing and deformation processing between the plurality of pieces of property distribution information corresponding to the plurality of lights; a spatial variance information obtaining unit configured to calculate a plurality of pieces of spatial variance information indicating a spatial variance, corresponding to the plurality of light, in the plurality of pieces of at least part of the oxygen saturation distribution information; and a decision unit configured to calculate positional derivation information between the subject and the converting element in a case where the spatial variance indicated by the spatial variance information is smaller than a predetermined value or the smallest from among the plurality of pieces of spatial variance information, wherein the second distribution obtaining unit is configured to calculate the oxygen saturation distribution information using the plurality of pieces of the property distribution information after the at least one of the coordinate shifting processing and the deformation processing in according to the positional derivation information.