Access authentication is important to the deployment and application of mobile IPv6 network, and Authentication in handover procedure will reduce handover performance in mobile IPv6 network. However, many studies for the access authentication in mobile IPv6 network ignore the effect of authentication in handover procedure. Furthermore, many certificate-based authentication schemes are not fit for the wireless mobile environment. To solve these drawbacks, a fast mutual authentication mechanism using Identity-based signature in mobile IPv6 network is proposed. The identity-based signature scheme uses NAI (network access identifier) as public key and simplifies the key management in wireless mobile environment, so it can resolve the deficiency in PKI-based authentication mechanism. An effective combination of the fast handover and authentication can minimize the additional load resulting from authentication in mobile procedure. Performance analysis results show that the proposed mechanism is more efficient than other schemes.