A portable terminal device includes a supporting leg which makes it possible to watch television in a standing state of the terminal device. The portable terminal device comprises a main body having a mounting groove formed in a rear surface thereof to have a predetermined length, the mounting groove having a plurality of catching grooves formed in one inner side surface thereof; and a supporting leg assembly having an end rotatably supported in the mounting groove. The supporting leg assembly comprises a supporting leg including a leg portion having a predetermined length, and a hollow head portion formed at one end of the leg portion and having one side opened. A cam member is inserted and supported in the head portion of the supporting leg with a spring received therein to be movable within a certain section in an axial direction. The cam member has a cam protrusion protruding outward to be caught to one of the catching grooves by an elastic force of the spring.