A portable electronic device including a main display and at least one external display detachable relative to one side of the main display is provided. The external display includes a body, a slider slidably disposed in the body, at least one latch pivoted to the body, and at least one elastic member connected between the slider and the body. The latch has a driving column and a tenon portion opposite to each other, and the driving column is movably connected to the slider, such that when the slider slides relative to the body, the latch is driven to pivot relative to the body, and the tenon portion is rotated out of the body or hidden in body. The tenon portion that is rotated out of the body is inserted into the main display, so that the external display is combined to the main display.