Most gels are polymer networks formed by long polymer chains and cross-linking agents that swell in a solvent. The cross-linkers bond the polymer chains together and prevent them from dissolving. Characteristic properties of gels, such as swelling/shrinking, elasticity, rheology/viscoelasticity, friction, chemical/physical sorption/desorption, and optical properties, are important from both academic and industrial perspectives, and have been the subject of much research. Since these gel properties are closely related to the gel structure, the structural analysis of gels is particularly important in the study of gels. However, due to the inherently heterogeneous structure of gels, structural analysis of gels has not been easy and has not been able to go beyond the realm of phenomenology. Finally, from the late 1990s to the beginning of this century, a systematic understanding of gels has been developed. In this chapter, we first describe the “static” structural analysis of gels by scattering methods such as X-ray/neutron/light scattering, morphological methods such as microscopy, and NMR, one of the spectroscopic methods. Then, the dynamic properties of gels by dynamic light scattering, i.e., “dynamic” structural analysis, is described, including theory and experiment, and various applications, such as gelation point determination methods.