1. A diagnostic imaging apparatus characterized by comprising: a measuring area setting unit, which sets, in the image plane, a plurality of measuring areas used for measuring body movement of a target object; a body movement measuring unit, which detects movement and deformation amounts in the measuring areas set by said measuring area setting unit; an image accumulating subtracting unit, which carries out accumulating or subtracting processing of a plurality of images, based on body movement measured by said body movement measuring unit; and an image display unit, which displays images processed by said image accumulating subtracting unit.