Recently, human body communication (HBC) which uses a human body as a signal transmission medium has drawn considerable attention as a promising technology to realize efficient and safe body area networks (BANs). However, in order to gain benefit from useful services based on so-called “big data”, the HBC needs connect to external wireless networks such as personal or local area network (PAN or LAN), because the HBC network is confined around the body. In this paper, utilizing wearable electrodes for HBC at a MHz-band as an antenna for wireless PAN and LAN at a GHz-band was propose. Furthermore, the reflection characteristics, electric field distributions and radiation efficiencies of the wearable electrodes in the broad frequency range of 5 MHz to 5.5 GHz were also investigated. As a result, the wearable electrodes, without any additional antenna elements or slits, showed the resonances at 1.03 GHz and 1.93 GHz with radiation efficiencies of 50.2 % and 39.5 %, respectively, for the wireless PAN and LAN. It is confirmed that the electrodes are usable not only for the HBC at MHz-band, but also for PAN and LAN at GHz-band.