An antenna structure includes a metal housing, a first resonance portion, a second resonance portion, an extending portion, and a signal feed source. The metal housing includes a front frame, a backboard, and a side frame. The side frame defines a slot and the front frame defines a groove and a gap. The metal housing is divided into at least an antenna section by the slot, the groove, and the gap. The first and second resonance portions and the extending portion are spaced apart from each other. The first resonance portion and the extending portion are both directly and electrically connected to the antenna section or are spaced apart and electrically coupled to the antenna section. The second resonance portion is electrically connected to the antenna section. One resonance portion is electrically connected to the signal feed source and the other resonance portion is grounded.