1. A photoacoustic apparatus comprising: a light source configured to generate a plurality of lights with mutually different wavelengths; a converting element configured to receive photoacoustic waves generated in a subject by the subject being irradiated by the plurality of lights; a first distribution obtaining unit configured to obtain a property distribution based on optical absorption within the subject, for each of the mutually different wavelengths, using time-sequence reception signals output from the converting element for each of the mutually different wavelengths; a second distribution obtaining unit configured to, using a plurality of property distributions based on optical absorption for each of the mutually different wavelengths, obtain a concentration-related distribution of a substance of an object region of the subject; and a statistical information obtaining unit configured to obtain statistical information indicating variance in distribution in at least a part of the concentration-related distribution; wherein the second distribution obtaining unit obtains, based on the statistical information, a concentration-related distribution where positional deviation between the object region and the converting element at each of the mutually different wavelengths is suppressed.