A photoacoustic apparatus includes an emitting unit that emits light onto an object； a receiving unit that receives a photoacoustic wave generated from the object irradiated with the light and outputs a signal； a first calculating unit calculates, based on the signal, an initial sound pressure distribution in a first region； a control unit causes the initial sound pressure distribution to be displayed； an acquiring unit acquires first information on a second region, designated within a region of the initial sound pressure distribution, and based on the first information, second information on a third region； a second calculating unit that calculates, based on the first information, propagation of the light in the third region to calculate a light fluence distribution in the second region； and a third calculating unit calculates, based on the initial sound pressure distribution and the light fluence distribution, an object information distribution in the second region.
