A subject information acquiring device includes a plurality of conversion element and a processing unit. Each of the plurality of conversion elements transmits acoustic waves as to a subject, receives reflected waves which have reflected within the subject, and converts the received reflected waves into time-sequence reception signals. The processing unit acquires information of within the subject by performing adaptive beam forming processing using a plurality of the reception signals. To output a plurality of times worth of reception signals based on each of a plurality of times of acoustic wave transmission, at least a part of the plurality of conversion elements perform acoustic wave transmission as to a predetermined region within the subject the plurality of times. In the adaptive beam forming processing, the processing unit performs integration processing of a plurality of correlation matrices obtained using the plurality of times worth of reception signals.
