Because the rupture risk for cerebral aneurysms is very low and comparable risk of surgical complications has been reported, it is very important to predict the rupture risk individually. Patient-specific simulations based on medical images such as CT and MRI enable us calculate hemodynamic and solid tensile stress acting on individual aneurysms, which play important roles in growth and rupture of aneurysms. In this paper, fluid-structure interaction (FSI) analyses of a cerebral aneurysm at the middle cerebral artery (MCA) bifurcation are presented. The peripheral vasculature model with a 0D structural recursive tree model is incorporated and coupled with the 3D FSI simulation to simulate outflow through two branches accurately. The results are compared with FSI simulation with prescribed pressure variation at the outlets. The comparison shows that the pressure at the two outlets are nearly identical and the flow division to the two branches is nearly the same as what we see in the simulation without the peripheral vasculature model. The results suggest that the role of the peripheral vasculature in the MCA aneurysm FSI is not significant.