In ultrasound images, there are many stationary echoes in the region superficial to the deep region comprising the heart. In the present invention, a HPF processing unit (20) filters frame data by applying a high pass filter, the characteristics of which have been set according to the depth in the frame, on the frame data at said depth. The high pass filter can be achieved, for example, with a digital filter and the characteristics of the high pass filter are adjusted by the filter-setting unit (22) setting the filter coefficient of said digital filter. That is to say, the filter coefficient in the HPF processing unit (20) is controlled by the filter-setting unit (22) so that the deeper the region, the higher the offset level is set.
