An ultrasonic diagnosing system includes a probe having an vibrator made of a plurality of spaced piezoelectric; material elements arranged in a matrix, first electrodes arranged on one surface of the vibrator in an array of rows parallel to each other, and second electrodes arranged on another surface of the vibrator in an array of rows parallel to each other and orthogonally to the first electrodes. Particularly, the piezoelectric material elements are spaced by spacer segments arranged between the electrode rows and formed from a high molecular weight material with less acoustic impedance than the piezoelectric material, a Shore hardness D50 or more (JIS) and a thickness of about 1/10 to 1/2 of the piezoelectric elements. The ultrasonic diagnosing system uses a phased array technique to provide tomograms at mutually orthogonal and spatially close positions with sufficient sensitivity.