There exist various biological macromolecular assemblies consisting of proteins, nucleic acids, sugars, lipids, and other substances in living cells. These macromolecular assemblies play key roles in all living system. Our laboratory works on structure determination of biological macromolecular assemblies, as well as proteins, which play important roles in biological system, using X-ray crystallography. Development of tools for X-ray crystal structure determination of biological macromolecular assemblies, including synchrotron radiation beamtime at SPring-8, is also one of our main works.