An antenna structure includes a circuit board and at least one antenna circuit. The circuit board includes a ground area and an antenna area. The antenna area is substantially rectangular-shaped and arranged between the ground area and the periphery of the circuit board. The antenna circuit is formed within the antenna area and includes a feeding segment, a border segment and at least one ground segment. The feeding segment is connected to the border segment and the distance from the border segment to the periphery of the circuit board ranges from 0 to 3 millimeters; a substantially 90° bent-structure is formed within the border segment. One end portion of the ground segment is connected to the ground area. Thus an antenna structure which enables the antenna circuit to be formed within the remaining space on the periphery of the circuit board is provided.