an ultrasound diagnostic apparatus for obtaining an ultrasound image of a subject into which an ultrasound contrast agent mainly composed of microbubbles is injected , comprising a probe configured to transmit / receive an ultrasound wave to / from the subject , a transmission circuit configured to drive the probe to transmit an ultrasound wave while sequentially changing a direction of an ultrasound transmission line , a reception circuit configured to generate reception line data of the number of parallel reception from ultrasound echo signals obtained by one ultrasound wave transmission , a transmission / reception control circuit configured to control the transmission and reception circuits to change the number of parallel reception during a scan sequence for generating a 1 - frame ultrasound image , and an image processing unit configured to generate an ultrasound image on the basis of the reception line data .