A mobile communication device includes a substrate, a metal frame, a feeding portion, and a parasitic portion. The substrate includes a ground plane and a non-ground area. The metal frame surrounds the substrate and includes a plurality of gaps to form a first frame element and a second frame element separated from each other. The first frame element is electrically connected to the ground plane. The feeding portion and the parasitic portion are located in the non-ground area. A first end of the feeding portion is configured to receive a feeding signal, and a second end of the feeding portion is an open end. The parasitic portion is electrically connected to the second frame element and the ground plane. The feeding portion, the second frame element, and the parasitic portion of the mobile communication device constitute a loop antenna.