To provide a superposition type portable terminal unit in which functions other than opening and closing functions are added to opening and closing operations thereby to improve the operating performance of the portable terminal unit. In a superposition type portable terminal unit in which a first housing having at least a display section and a second housing having at least an operation section, in a close state where the display section and the operation section face in the same direction and the housings are superimposed on each other so that the operation section of the second housing is covered with the first housing, are coupled at their ends by a coupling part having an axis in a direction where the both housings are pierced, the unit is put in an open state in case that the first housing is turned about the axis from the close state in any of a clockwise direction and a counterclockwise direction; and a control unit is provided, which selects a screen so that a first screen is displayed in the display section in case that the first housing is turned in relation to the second housing clockwise from the close state, and so that a second screen is displayed in the display section in case that the first housing is turned in relation to the second housing counterclockwise.