In an ultrasonic probe which acquires an elasticity image while pressing a subject, a contact surface which extends perpendicular to a pressing direction and which comes into contact with the subject is provided. Further, automatic pressing means configured to press a to-be-imaged portion of the subject with a predetermined pressure by moving the contact surface in the pressing direction or manual pressing means for applying a pressing force by manpower is provided. By use of the ultrasonic probe including the automatic pressing means or the manual pressing means, the pressing stage can be automatically or manually moved in a fixed vertical direction at a desired speed. A high-quality elasticity image data can be acquired at an arbitrary time. Furthermore, since repeatability of the pressing action can be maintained, the problem of the quality of the elasticity image being dependant on the technician can be avoided.
