In this talk, I will introduce the notion of weakly unobstructed Lagrangian submanifolds and balanced Lagrangian submanifolds. I will explain construction of certain potential function constructed out of study of deformation theory of Floer cohomology and explain its relationship to the earlier work of Givental which advocates that quantum cohomology ring is isomorphic to the Jacobian ring of Landau-Ginzburg superpotential. I will explain these result in the context of mirror symmetry between Fano toric A-model and Landau-Ginzburg B-model. If time permits, I will indicate how this study can be related to construction of Entov-Polterovich's symplectic quasi-states on toric manifolds. This is a joint work with Fukaya, Ohta and Ono.