A mobile terminal and controlling method thereof are disclosed, by which a user interface for appreciating a 3-dimensional (3D) stereoscopic image more conveniently can be provided. The present invention includes a display unit including a parallax generating means for displaying a 3D stereoscopic image on at least one portion of the display unit and a controller, when a planar (2D) image is displayed via the display unit, determining whether the 3D stereoscopic image is outputted via the display unit within a preset duration, the controller, if the 3D stereoscopic image is outputted as a result of the determination, controlling a prescribed visual effect indicating that the 3D stereoscopic image is outputted to be given to at least one region of the display unit.