A motion parameter measuring unit two-dimensionally measures a motion parameter of a myocardial tissue by a tracking process on time-series ultrasonic image data acquired from a sample. A time phase setting unit adds a diastolic heartbeat time phase, which is set on the basis of a systole end specified by a time phase where a cardiac cavity area of the ultrasonic image data is the smallest and a diastole end specified by an R wave in an electrocardiographic waveform of the sample, relative to the systole end to time-series parameter image data generated by a parameter image data generating unit on the basis of the motion parameter. An image data extracting unit extracts parameter image data to which the diastolic heartbeat time phase closest to a desired diastolic heartbeat time phase set by an input unit is added and displays the extracted parameter image data.