A plurality of transmit foci (a plurality of virtual sources) (F1-F7) are formed upon a scan plane with a two-dimensional pattern. Specifically, first transmission beams having first transmission foci and second transmission beams having second transmission foci are formed alternately in a scan direction. A plurality of first sub-images (LRI1, LRI3, LRI7) are formed by the forming of the plurality of first transmission beams, and a plurality of second sub-images (LRI2, LRI4, LRI6) are formed by the forming of the plurality of second transmission beams. At time of reception, a parallel reception technology is applied.
