We study the evolution of the emerging and eruptive Active Region (AR) 10930 for which the coronal magnetic field is reconstructed as a nonlinear force-free field along with vector magnetograms obtained from Hinode/SOT/SP data. We show that the AR evolves quasi-statically during several days through a sequence of equilibria until the time of the eruption. In addition this sequence emphasizes the formation and expansion of a coronal Twisted Flux Rope (TFR) which is related to other observed coronal structures. On the other hand, the pre-eruptive and post-eruptive magnetic configurations show that the pre-eruptive TFR plays a crucial role during the eruption.