A portable electronic device is provided. The portable electronic device includes a display unit, an input unit, and a hinge mechanism. The hinge mechanism is detachably connected the display unit and pivotally connected to the input unit, wherein the hinge mechanism includes a housing, a stopper, and an elastic element. The elastic element connects the housing to the stopper. When the portable electronic device is in a closed state, the stopper is in an initial position relative to the housing. When the display unit and the hinge mechanism are rotated relative to the input unit around a rotation axis and the portable electronic device is in an open state, the elastic element exerts an elastic force on the stopper, and the stopper slides to an outer side relative to the housing from the initial position and partially covers the display unit.