1. A method of obtaining symmetry information of objects, the method comprising: acquiring at least one second feature point matched to at least one first feature point of the objects, which are extracted from an ultrasound image of the objects, from a mirror image obtained by reversing the ultrasound image based on an arbitrary axis; acquiring a third feature point corresponding to a location of the second feature point in the mirror image from the ultrasound image; determining a symmetry axis of the objects by using a center point between the first feature point and the third feature point; and acquiring symmetry information indicating whether the objects are symmetrical about the determined symmetry axis.