A multi-band antenna includes a circuit board having an insulation dielectric layer, a first ground plane and an impedance matching circuit formed on a first plane of the circuit board, and a second ground plane formed on a second plane of the circuit board. A slot antenna radiation main body, formed at a location of the second ground plane and corresponding to the exposed part of the insulation dielectric layer, includes first and second radiation main bodies. The first radiation main body includes a first impedance matching part and a first resonance part. The second radiation main body includes a second impedance matching part and a second resonance part. The first resonance part includes a plurality of first bends, a first segment, and a second segment. The second resonance part includes a plurality of second bends, a third segment, and a fourth segment.