An object information acquiring apparatus comprises a light irradiation unit configured to irradiate an object with light； a sound generating member arranged between the object and the light irradiation unit and configured to generate a substantially planar ultrasonic wave based on the irradiated light； an acoustic wave probe configured to acquire an acoustic wave generated inside the object due to the light and convert the acoustic wave into a first electric signal； and an information generating unit configured to generate information concerning optical characteristics of an interior of the object, based on the first electric signal, wherein the sound generating member allows a part of the light irradiated from the light irradiation unit to pass through the sound generating member to the object.
