A dual-band antenna utilized in a wireless communication device for receiving or transmitting wireless signals of a first frequency band and a second frequency band includes a rectangular metal plane formed with a slot structure substantially extending from a first side to a second side of the rectangular metal plane, a feeding terminal formed on the rectangular metal plane, and a grounding element, disposed on a third side or a fourth side of the rectangular metal plane, for electrically connecting the rectangular metal plane and a system ground of the wireless communication device, wherein the first side is substantially parallel to the second side, the third side is substantially parallel to the fourth side, and the first side is substantially perpendicular to the third side or the fourth side.