An object information acquiring apparatus includes a probe configured to irradiate ultrasonic waves to an object, receive ultrasonic echoes, and convert the ultrasonic echoes into electric signals, a scanning unit configured to cause the probe to perform back-and-forth scanning on the object, an ultrasonic control unit configured to control irradiation of ultrasonic waves, a signal processing unit configured to obtain an ultrasonic, and a combining unit configured to combine a plurality of ultrasonic images. The scanning unit causes the probe to perform back-and-forth scanning on the object such that regions subjected to ultrasonic irradiation performed by the probe in forward and backward paths in the back-and-forth scanning overlap with each other. The ultrasonic control unit employs different methods for irradiating ultrasonic waves in the forward and backward paths. The combining unit combines a plurality of ultrasonic images with one another.