An diagnostic imaging apparatus for imaging information changing with time and displaying it in real time, composed of an ultrasonic probe (2), having piezoelectric elements arranged in an array form that transmit ultrasonic waves to a target object (1) and acquires a reflection signal from the target object; a body movement measuring unit (12) that constitutes a two-dimensional ultrasonic image using the reflection signal acquired by the ultrasonic probe, sets, in the image plane, a plurality of measuring areas used for measuring the body movement of the target object, and measures the body movement and deformation amounts in the measuring areas; and an image accumulating (subtracting) unit for accumulating or subtracting images using body movement measured by the body movement measurement unit.