A single-layer dual-band antenna with circular polarization is disclosed. The antenna includes a first radiator formed on the top surface of a substrate and electrically coupled to a feeding element, and a second radiator formed on the top surface of the substrate, spaced apart from the first radiator by a predetermined distance and electromagnetically coupled with the first radiator. The antenna is thin because it has a single-layer structure. Furthermore, there is no deterioration in the radiation characteristic due to interference between the radiators. Moreover, impedances of the radiators can be independently matched at their frequency bands by adjusting the position of a feed point and the relative position of the radiators.