1. An apparatus for generating a stereoscopic image from a two-dimensional (2D) image by using a mesh map, the apparatus comprising: a reception unit for receiving the 2D image including a still image or a moving picture from an external device and receiving mesh shapes and depth information of a mesh map which are edited by a user; a screen reference unit for displaying the 2D image and the mesh map; an information management unit for managing the mesh shapes and the depth information of the mesh map that is edited by the user in accordance with shapes of a displayed image; a calculation unit for calculating relative depth information of the 2D image by calculating an average relative depth value for each pixel of the 2D image by calculating: an x-coordinate value and a y-coordinate value of each corner of the mesh map; a distance rate from each pixel to each corner of the mesh map; a z-coordinate depth value for each corner of the mesh map based on the mesh map edited by the user; product values of inverse-proportionally multiplying the z-coordinate depth value of each corner of the mesh map by the distance rate of each corner of the mesh map from the pixel; and an average of the product values; and a stereoscopic image generation unit for generating a stereoscopic image file by using the calculated relative depth information of the 2D image.