An apparatus and method for processing an echocardiogram using the Navier-Stokes equation is provided. The apparatus includes an ultrasonic sensor that transmits ultrasonic waves to the heart in three different directions and receives echoes thereof; an image processor that constructs first to third echocardiograms captured from the three different directions, respectively, based on the received echoes of the ultrasonic waves; a three-dimensional model construction unit that constructs a three-dimensional model of a left ventricle of the heart based on the first to third echocardiograms; and a blood flow vector calculation unit that calculates blood flow vectors within the left ventricle by applying the three-dimensional model of the left ventricle to boundary conditions in the Navier-Stokes equation. In echocardiogram processing, vector components of the blood flow within the left ventricle are calculated using the Navier-Stokes equation, whereby the vector components of the blood flow can be more accurately calculated.