An ultrasonographic device is equipped with selecting means for selecting a site for detecting the position of a boundary of an organ of the examinee on the ultrasonic image displayed on the display means, boundary extracting filter setting means for setting a boundary extracting filter comprising two areas which are spaced from each other at a predetermined interval on the ultrasonic image, and boundary position detecting means for analyzing pixel data within the boundary extracting filter set by the boundary extracting filter setting means in the neighborhood of the site selected by the selecting means to detect the position of the boundary, the boundary position detected by the boundary position detecting means being displayed on the display means under the control of the control means.
