Wireless Power Transfer (WPT) has been attracting attention as one of the solutions of EV charging. In recent years, many researches have used the kHz band, however the size of antenna becomes large. To solve the sizing problem, using industrial, scientific, and medical (ISM) bands;13.56MHz is a good solution. However, the example of antenna design which achieve high efficiency about 90% with over 200mm transfer distance has not been reported. In addition, there is no report of high power transmission over 1kW. In this paper, an antenna design method is proposed and the method is experimentally confirmed. In addition, this prototype antenna can transfer about 2.5kW electrical power with 89.3% antenna efficiency under 300mm transmission distance in the experiment.