In this text, the authors introduce two powerful techniques and one developing one for Small-Angle Neutron Scattering (SANS). The most fascinating feature of neutron as a scattering probe is its isotope effect in hydrogen. The first topic is concerning about recent progress on Contrast Variation Method: the author shows how to apply the contrast variation method to protein-mineral complex system and analyze the data. The second is concerning about deuteration-labeling: the author shows kinetics analysis in quaternary structure of homo-oligomeric protein with this technique. The final topic is concerning about the next generation analysis: an analysis method coupling SANS with neutron spin echo for dynamics of tertiary structure of protein.