A portable electronic device comprises a cover and a body. The cover comprises a first end wall, a second end wall opposite to the first end wall, and a sidewall connecting the first end wall and the second end wall. The sidewall defines a sliding slot. Two ends of the sliding slot respectively extend to the first end wall and the second end wall. The body comprises a protrusion formed thereon. The protrusion is slidably received in the sliding slot. The protrusion slides to the first end wall or the second end wall, whereby the cover hinges on the protrusion relative to the body.