A mobile device includes a dielectric substrate, a ground element, a signal source, a first conductive frame, a second conductive frame, a third conductive frame, a shorting element, a feeding element, a first radiation element, and a second radiation element. The first conductive frame, the second conductive frame, and the third conductive frame are separate from each other. The second conductive frame is coupled through the shorting element to the ground element. The first radiation element is coupled to the feeding element. An open end of the first radiation element is adjacent to the second conductive frame. The second radiation element is coupled to the feeding element. An open end of the second radiation element is adjacent to the third conductive frame. An antenna structure is formed by the feeding element, the first radiation element, the second radiation element, the shorting element, and the second conductive frame.