A portable electronic device includes an expansion base module with a connector, a hinge mechanism mounted slidably on the expansion base module, slidable relative to the expansion base module, and including a pivot shaft, a system module pivoted to the expansion base module through the pivot shaft, and a ribbon cable having a first segment that is electrically connected to and that extends from the connector toward the pivot shaft, and a second segment that extends from the first segment, that is wound around the pivot shaft, and that is electrically connected to the system module.