An ultrasonic diagnostic device includes an ultrasonic probe and processing circuitry. The probe conducts ultrasonic scanning on a three-dimensional area of a subject and receives a reflected wave from the subject. The circuitry acquires the correspondence relation between a position in ultrasonic image data on the three-dimensional area based on the reflected wave and a position in volume data on the subject captured by a different medical-image diagnostic device. The circuitry receives, from an operator, an operation to set a position marker, which indicates the position at which blood-flow information is extracted, on a scan area of the ultrasonic image data. The circuitry causes the image generated during a rendering process on the ultrasonic image data to be displayed and causes the position marker to be displayed at a corresponding position on a display image based on at least the volume data in accordance with the correspondence relation.
