A swing hinge device of a portable terminal is adapted to semi-automatically rotate a pair of housings of the terminal while they face each other to open and close them. The swing hinge device of a portable terminal having a first housing and a second housing includes a hinge housing extending along a longitudinal direction and having a reception space formed therein. A hinge shaft is rotatably coupled to the hinge housing and has a number of crests formed thereon. A hinge cam is positioned in the reception space of the hinge housing and is adapted to linearly travel therein along the longitudinal direction of the hinge axis and has a number of troughs formed thereon that face the respective crests. A hinge spring is positioned between the hinge housing and the hinge cam to provide an elastic force so that the hinge cam may linearly travel while forcing it against the hinge shaft A hinge stopper portion is positioned between the hinge housing and the hinge shaft to limit the range of rotation of the hinge shaft that rotates in the hinge housing.