An antenna structure includes a radiation element, a grounding element, a short point, and a feeding point. The radiation element includes a first radiator and a second radiator. The second radiator partially surrounds the first radiator and there is a predetermined distance included between the first radiator and the second radiator for matching impedance. The short point is coupled between the second radiator and the grounding element. The feeding point is coupled between a joint point of the first radiator and the second radiator and the grounding element.