Provided is an object information acquiring apparatus including: a probe in which a plurality of elements transmitting an ultrasound wave to a measurement target region of an object and receiving a reflected wave is arranged in a first direction a mechanical scanning unit that moves the probe in the first direction and a direction crossing the first direction a transmission processor that, to each element included in a transmission aperture element row transmitting the ultrasound wave, inputs an input signal for driving the element a received signal processor that combines received signals obtained by the elements included in a reception aperture element row receiving the ultrasound wave a generator that generates property information on the object from the combined signal and a controller that determines at least one of the number of elements included in the transmission aperture element row.
