An unlock method for conveniently releasing a lock mode of a mobile terminal includes tracking a trajectory corresponding to a touch-and-drag operation of touching the touch screen and then dragging when the mobile terminal is in a lock mode, determining whether one or more intersections occur on the trajectory, and releasing the lock mode if one or more intersections occur on the trajectory. Accordingly, a touch input pattern for unlocking a lock mode is unlimited in terms of size, location, and pattern so that a user can freely touch the touch screen to release the lock mode.