An apparatus and a method process a stereoscopic image. More particularly, an apparatus and a method improve compression performance of stereoscopic image data in a portable terminal. The apparatus includes a camera unit including at least two camera modules spaced about a certain distance apart. The camera unit is configured to obtain a first image and a second image to be used to constitute stereoscopic image data. The apparatus further includes a three-dimensional (3D) data generation unit configured to change a compression ratio of the first image and the second image obtained by the camera unit.