Ultrasonic imaging device noninvasively measures cardiac muscle stiffness or intracardiac pressure. The device includes: an ultrasonic probe (2) transmitting and receiving ultrasonic waves to and from the heart; a signal-processing section (15) processing reflected echo signals; a display section (14) displaying results of signal processing as an image; and an input section (10) setting a predetermined point on the image. The signal-processing section (15) includes: a shape-extracting section (152) perceiving information on the shape of the heart from the reflected echo signals; a natural-frequency detecting section (153) detecting natural frequency of the heart from the reflected echo signals; and a calculating section (154) calculating stiffness of the cardiac muscle or the intracardiac pressure, wherein the calculating section (154) accurately calculates the stiffness of the cardiac muscle from the natural frequency of the heart and calculates the intracardiac pressure from the stiffness of the cardiac muscle that has been calculated.