Recently, Botnet has been used to launch spam-mail, key-logging, and DDoS attacks. Botnet is a network of bots which are controlled by attacker. A lot of detection mechanisms have been proposed to detect Botnet on wired network. However, in IP based sensor network environment, there is no detection mechanism for Botnet attacks. In this paper, we analyze the threat of Botnet on 6LoWPAN and propose a mechanism to detect Botnet on 6LoWPAN.