Secure and reliable group communication is an increasingly active research area by growing popularity in group-oriented and collaborative applications. In this paper, we propose the first identity-based authenticated group key agreement in multiple private key generators (PKG) environment. It is inspired on a new two-party identity-based key agreement protocol first proposed by Hoonjung Leeet al. In our scheme, although each member comes from different domain and belongs to different PKGs which do not share the common system parameters, they can agree on a shared secret group key. We show that our scheme satisfies every security requirements of the group key agreement protocols.