A convertible mobile device includes an upper cover, a base, a hinge element, a supporting element, an antenna structure, and a cover element. The hinge element is connected between the upper cover and the base, so that the convertible mobile device can flip over and operate in a notebook mode or a tablet mode. The antenna structure is disposed on the supporting element. The antenna structure includes a first radiation element and a second radiation element. One of the first radiation element and the second radiation element has a positive feeding point, and the other of the first radiation element and the second radiation element has a negative feeding point. A coupling gap is formed between the first radiation element and the second radiation element. The cover element covers the supporting element, the antenna structure, and at least a portion of the hinge element.