A small antenna, which is used in a mobile radio communication apparatus such as a portable telephone, operating in a broader frequency band a conventional antenna, operating corresponding to plural frequencies, and being disposed in a case is provided. The radio communication apparatus including the antenna is also provided. The antenna includes a first conductive radiator having a planer shape, a second conductive radiator having a helical shape, and a planar feeding section that is disposed between the first conductive radiator and the ground plane, is isolated from them, and supplying power by electromagnetic coupling.