1st and 2nd pulsed waves are transmitted along 1st and 2nd transmit beams where at least one of the beams is broad in at least one direction, and the transmit timing between said 1st and 2nd pulsed waves are selected so that the pulsed wave fronts overlap in an overlap region R that propagates along at least one measurement or image curve \u0393 in the material object. The power consumption of the set-top box can be reduced by receiving the information of a connected video terminal from a TV and controlling the other video terminals based upon the information. Thus, the user can intuitively recognize the sub-data contained in the document A.