A method and an apparatus for modifying a contour line of an object are provided. The method involves displaying a contour line of an object on a screen, receiving a plurality of touch points, matching each of the plurality of the received touch points with corresponding contour line points on the contour line, generating touch point movement data by tracing a movement path of each of the plurality of the received touch points, determining a curvature variation of the contour line based on the touch point movement data, and modifying the contour line by moving each of the corresponding contour line points based on the touch point movement data and applying the curvature variation to a section connected between each of the moved corresponding contour line points to generate the section.