1. An ultrasound imaging apparatus, comprising: a scanner configured to transmit ultrasound waves to a subject and receive reflected waves from the subject; an image generator configured to generate tomographic image data based on the reflected waves; a marker generator configured to generate a first marker of a first scan range and a second marker of a second scan range; and a display controller configured to cause a display to display each of a tomographic image based on the tomographic image data, the first marker, and the second marker, and cause the display to display both of the first marker and the second marker so as to be superimposed on the tomographic image in a state that the second marker is included in the first scan range of the first marker, wherein: the scanner is configured to execute scan with ultrasound waves on the range specified based on the first marker; and the image generator is configured to generate three-dimensional image data based on, of data acquired in the scan, data included in a range specified based on the second marker.