An ultrasound image acquiring device is provided for making it possible to easily display a three-dimensional image included in a region of interest (ROI). A display control unit (9) makes a display unit (10) display a tomographic image and, further, makes the display unit (10) display a first marker indicative of a three-dimensional scanning scope and a second marker indicative of a three-dimensional image data forming scope (the scope subjected to rendering processing) overlapped with the tomographic image. The second marker is set to be rotatable on the tomographic image in accordance withan instruction of an operator. A transmitting and receiving unit (3) scans the scanning scope specified in accordance with the first marker by an ultrasound probe (2). Out of the data acquired by thescanning, an image processing unit (7) carries out the rendering processing for data that are included in the scope specified in accordance with the second marker and generates three-dimensional image data.