A mobile device includes a host upper cover, a host lower cover, a metal cavity structure, a protruding radiation element, a nonconductive connection element, and a feeding element. The metal cavity structure is coupled between the host upper cover and the host lower cover. The metal cavity structure includes a first metal partition and a second metal partition. The first metal partition has an opening. The nonconductive connection element is connected to the edge of the opening of the first metal partition. The nonconductive connection element is configured to support and surround the protruding radiation element. The feeding element is coupled to a signal source and is disposed adjacent to the protruding radiation element. An antenna structure is formed by the feeding element and the protruding radiation element.