A dual-band circularly polarized antenna is disclosed, more particularly a dual-band circularly polarized antenna being able to transmit and receive circularly polarized signals at two different frequency bands, simultaneously. The dual-band circularly polarized antenna of the present invention comprises a first polarized radiating element with at least one corner being chamfered, a plurality of second polarized radiating elements with each of the second polarized radiating elements having at least one corner being chamfered, a signal distributor for distributing an electrical signal, a signal coupling unit electrically connecting with the first polarized radiating unit and the signal distributor, and a ground plate. The dual-band circularly polarized antenna of the present invention not only can be manufactured with a low cost, but also has a simpler structure. As a result, the dual-band circularly polarized antenna of the present invention can be easily integrated into the antenna module of an RFID system.