A mobile terminal including a display unit configured to display at least a first 3D object at a first 3D depth level and a second 3D object at a second 3D depth level that is different than the first 3D depth level; and a controller configured to receive a first selection action on the first 3D object and a second selection action on the second 3D object image, to convert the second 3D depth level of the second 3D object to match the first 3D depth level of the first 3D object based on the first and second selection actions, and to control the display unit to display the first and second 3D objects at the first 3D depth level.