An ultrasonic diagnosis system comprising: an ultrasonic probe for performing transmission/reception of ultrasonic signals to/from a subject; storage means for storing envelope signals detected by a quadrature detector from the ultrasonic signals obtained by said ultrasonic probe; correlation computing means adapted to set measurement points separated by a predetermined pitch of half a wavelength of the ultrasonic signals or smaller in an axial direction of the ultrasonic beam on ultrasonic beam data formed of said stored envelope signals detected with and without pressure applied to said subject, calculate the position of each measurement point which exhibits the maximum correlation coefficient between said envelope signals with and without application of pressure by varying said measurement points in said axial direction of the ultrasonic beam at said predetermined pitch and in an ultrasonic-beam scanning direction orthogonal to said axial direction at the ultrasonic-wave beam-line pitch, and calculate a phase difference between said envelope signals with and without application of pressure; computing means (94 to 97) for calculating a displacement of each measurement point and the strain distribution of the tissue of said subject based on said displacement due to said application of pressure; and display means for displaying said strain distribution, wherein said computing means (94 to 97) include an axial-direction displacement computing means for calculating an axial displacement of each measurement point due to said application of pressure based upon the position which exhibits said maximum correlation coefficient and said phase difference calculated by said correlation computing means, characterised in that said computing means (94 to 97) further include an ultrasonic-beam scanning direction displacement computing means for estimating an ultrasonic-beam scanning direction displacement of each measurement point due to said application of pressure based upon the calculated position which exhibits said maximum correlation coefficient. an ultrasonic probe for performing transmission/reception of ultrasonic signals to/from a subject; storage means for storing envelope signals detected by a quadrature detector from the ultrasonic signals obtained by said ultrasonic probe; correlation computing means adapted to set measurement points separated by a predetermined pitch of half a wavelength of the ultrasonic signals or smaller in an axial direction of the ultrasonic beam on ultrasonic beam data formed of said stored envelope signals detected with and without pressure applied to said subject, calculate the position of each measurement point which exhibits the maximum correlation coefficient between said envelope signals with and without application of pressure by varying said measurement points in said axial direction of the ultrasonic beam at said predetermined pitch and in an ultrasonic-beam scanning direction orthogonal to said axial direction at the ultrasonic-wave beam-line pitch, and calculate a phase difference between said envelope signals with and without application of pressure; computing means (94 to 97) for calculating a displacement of each measurement point and the strain distribution of the tissue of said subject based on said displacement due to said application of pressure; and display means for displaying said strain distribution, wherein said computing means (94 to 97) include an axial-direction displacement computing means for calculating an axial displacement of each measurement point due to said application of pressure based upon the position which exhibits said maximum correlation coefficient and said phase difference calculated by said correlation computing means, characterised in that said computing means (94 to 97) further include an ultrasonic-beam scanning direction displacement computing means for estimating an ultrasonic-beam scanning direction displacement of each measurement point due to said application of pressure based upon the calculated position which exhibits said maximum correlation coefficient.