The present invention employs an acoustic imaging apparatus comprising a plurality of receiving elements (5) which receive acoustic waves (7) emitted from an object (P) and convert the acoustic waves into received signals, a delay unit (8) which matches phases of the received signals, a complex converter (9) which converts the received signals into complex signals, a complex covariance matrix calculator (M) which periodically obtains a complex covariance matrix by using a complex signal group configured from a plurality of phase -matched complex signals, an eliminator (14) which eliminates the number of bits of input data configured from at least either the complex signal group or matrix elements, and an electric power calculator (12) which calculates a power of target positions, wherein the eliminator eliminates the number of bits by performing common level conversion processing on all input data relating to one complex covariance matrix.
OBJECT INFORMATION ACQUIRING APPARATUS