An ultrasound diagnostic device includes a plurality of channels configured to receive data and a scan line data forming unit including a plurality of sub-scan line data forming groups and a data summing unit. The sub-scan line data forming group forms partial data of scan lines, and the data summing unit forms scan line data of the scan lines by summing the partial data. The sub-scan line data forming group includes a plurality of sub-scan line data forming units for forming the partial data of the scan lines by using the receiving data and providing a transmission path of the receiving data. First data lines transmit the receiving data between at least one of the sub-scan data forming unit and the channels, and second data lines transfer the receiving data between the sub-scan line data forming units.