An antenna structure includes a substrate, a metal element, and a feeding element. The metal element has an open slot. The open slot forms a first resonant path. The substrate is disposed on the metal element. The feeding element is disposed on the substrate, and the metal element and the feeding element are respectively disposed on two opposite sides of the substrate. The feeding element includes a feeding end and a shorting end electrically connected to the metal element. An orthogonal projection of the feeding element on the metal element is partially overlapped with the open slot. The feeding element forms a second resonant path extending from the feeding end to the shorting end. The antenna structure operates in a first band through the first resonant path and operates in a second band through the second resonant path.