A dual-band antenna is disposed on a substrate having an antenna-mounted surface. The dual-band antenna includes a first radiating unit, a second radiating unit, and a feeding terminal. The first radiating unit is disposed opposite to the antenna-mounted surface of the substrate, and at least has a first side, a second side and, a third side. The first side is opposite to the third side, and the length of the first side is not equal to that of the third side. The second side is connected to the first side and the third side. The second radiating unit is connected to the first side of the first radiating unit. The feeding terminal is connected to the third side of the first radiating unit and the antenna-mounted surface of the substrate.