A mobile device includes a nonconductive mechanism element and an antenna structure. The antenna structure is formed over the nonconductive mechanism element. The antenna structure includes a feeding connection element, a first radiation element, a second radiation element, a grounding connection element, and a third radiation element. The feeding connection element is coupled to a feeding point. A first end of the first radiation element is coupled to the feeding connection element, and a second end of the first radiation element is open. A first end of the second radiation element is coupled to the feeding connection element, and a second end of the second radiation element is open. The grounding connection element is coupled to a grounding point. A first end of the third radiation element is coupled to the grounding connection element, and a second end of the third radiation element is open.