Physical properties of functional ceramics are often originated from nanostructure in the materials. Therefore, I have studied nanostructures in detail to understand microscopic origin of the properties. Two of our examples will be in the present paper. Our systematic bicrystal studies clarified the microscopic origin of nonlinear current-voltage properties, a reason for stable structural-unit arrangements, and a dominant factor that determines location of dopant element in grain boundaries of zinc oxide. In another example, polar structure in ferroelectric and its response to an electric field was visualized. In the morphotropic-phase-boundary ferroelectric, Pb(Mg1/3Nb2/3)O3−PbTiO3, lead ion shifted from the crystal lattice corner forming ferroelectric order with width of ten-nanometer scale in a monoclinic phase. Applying an electric field caused reorientation of the ferroelectric order and removal of the field let the order move back to the original state. This observation explained a reason for low-hysteresis strain-electric-field curve that is suitable for sensor and actuator application.