An object of the present invention is to provide an antenna of small size which is excellent in the response characteristic in the high-frequency band, and to provide a communication device including the antenna having such an excellent characteristic that it is possible to realize downsizing of the device as a whole. That is, the present invention is directed to an antenna characterized by including a radiator made up of a carbon nanotube, and as a specific structure, for example, an antenna characterized by including an electrode that is connected with a part of the carbon nanotube and operates as a monopole antenna, and a communication device including the antenna.