An apparatus that acquires specific information on a subject on the basis of a signal originating from an acoustic wave which has propagated from the subject and propagated through an acoustic medium disposed between the subject and a receiving unit is provided. The apparatus includes: a wave number acquiring unit acquiring a spatial wave number component of the signal； a correcting unit correcting the spatial wave number component using parameters of a longitudinal wave velocity in the subject and a transverse wave velocity in the acoustic medium； and an information acquiring unit acquiring the specific information using the corrected spatial wave number component.
