An apparatus and method for controlling a portable device. An apparatus for controlling a portable device includes: a touch sensor which comprises at least one touch cell which is chosen by a touch of a user; a first calculation unit which calculates a first probability value while taking dependency relationships among the chosen at least one touch cell into consideration; a second calculation unit which calculates a second probability value without taking the dependency relationships among the chosen at least one touch cell into consideration; a determination unit which determines whether a current touch cell combination of the chosen at least one touch cell is a registered touch cell combination or an unregistered touch cell combination with reference to the first probability value and the second probability value; and an output unit which outputs a function execution signal according to the results of the determining.