According to one embodiment, a reception unit generates reception beam data set groups based on echo signals. Each of the reception beam data set groups includes reception beam data sets respectively corresponding to reception beams associated with parallel signal processing. Each of the reception beam data sets is generated based on echo signals from transducers associated with a corresponding reception position. A scanning control unit sets the spatial arrangement of the reception beams. The reception beams are arranged at unequal intervals. A synthesizing unit generates synthetic beam data sets associated with reception positions based on the reception beam data set groups. Each of the synthetic beam data sets is obtained by synthesizing reception beam data sets associated with the same reception position. An image generation unit generates ultrasonic image data based on the synthetic beam data sets.