In order to know the complicated functions and various properties of biomolecules, it is necessary to investigate long-time dynamics of them. Because the long time molecular dynamics simulations require the enormous force calculations, the precision of the force field parameter is very important. In addition, an unified force field is needed for different kinds of biomolecules such as proteins and lipid membranes interact in a complex way in our body. In a conventional force field developed for each type of biomolecule, the complex can not be modeled accurately. In our group we are developing unified force field parameters that can calculate biomolecular complexes with high accuracy.