The absolute pressure inside the heart with respect to heartbeat time phase is measured non-invasively or with minimal invasion. An ultrasonic diagnostic device comprising: a pressure sensor that detects artery pressure non-invasively； a reference pressure computation part that converts the artery pressure into absolute reference pressure with respect to a reference point； a spatial pressure difference calculation part that calculates a spatial pressure difference between the reference point and a location distinct from the reference point； and an absolute pressure computation part that calculates intracardiac absolute pressure using a shape image, the reference pressure, and the spatial pressure difference.
