A portable electronic device including a computer body, a display, and a slide-rail structure is provided. The computer body has a first side edge. The display has a second side edge, a display surface and a back side surface. The slide-rail structure includes a sliding element and a connecting arm. The sliding element having a first combination portion is slidable between a first and a second position. The connecting arm having a second combining portion connected to the first combining portion is rotatably connected to the second side edge. When an included angle between the display surface and the computer body is first angle, the sliding element is in the first position; when the included angle is varied from the first angle to an angle greater than the first angle, the connecting arm pulls the sliding element to the second position. In addition, a slide-rail device is also provided.