In this letter, we propose frequency diverse array (FDA) antenna for secure communication and study the secrecy capacity over Nakagami-m fading channels. The closed form approximate expression for the average secrecy capacity of artificial noise-aided FDA secure communication is derived. The correctness of the proposed analysis is verified by numerical results. It is shown that the proposed FDA scheme significantly enhances the communication security and outperforms conventional phased-array communications in the range dimension. Moreover, the impacts of fading severity parameters and power allocation factor on the system secrecy performance are also analyzed.