A portable electronic device includes an electronic paper, a case, a guiding mechanism, an assembling mechanism, a mobile communication module, a first support structure and a second support structure. The guiding mechanism is disposed in the case to form a guiding space. The assembling mechanism is disposed in the guiding mechanism. The assembling mechanism includes a flexible connecting part and a driving part. The driving part is connected to the electronic paper and the flexible connecting part for rolling the flexible connecting part to contain the electronic paper in the guiding space. The first and second support structures are pivoted to two ends of the case respectively and form a support rail. A connecting socket on the first support structure is electrically connected to the mobile communication module. The electronic paper moves along the support rail to connect to the connecting socket upon the stretching state.