Observational progress in precision cosmology these days is extraordinary. Recent observations, such as cosmic microwave background radiation by Planck satellite, show that the standard model of cosmology works amazingly well. However, true natures of dark matter and dark energy, which are critical elements in the standard model are not identified yet. There are many future observation plans for the large-scale structure (LSS) of the universe, with which we can study cosmology from new angles than before. Although theoretical developments to precisely describe LSS are required, there are subtle issues such as nonlinear structure formation and galaxy biasing, etc. I have been developing a theoretical approach called "integrated Perturbation Theory (iPT)" as a general framework to study the observables of LSS. In this talk, I will review recent theoretical developments of the LSS and some topics of iPT.