In this paper, we study the global nonexistence of solutions to a nonlinear wave equation with critical potential V(x) on a Riemannian manifold, the form of which is more general than those in (Todorova and Yordanov in C.R. Acad. Sci., Ser. 1 Math. 300: 557-562, 2000). The way we follow is motivated by the work of Qi S. Zhang (C.R. Acad. Sci., Ser. 1 Math. 333: 109-114, 2001). We also prove the local existence and uniqueness result.