Solvent models and sampling schemes for obtaining average physical properties for molecules in solution utilizing combined quantum mechanical / molecular mechanical (QM/MM) method are reviewed and a new sampling scheme of ours is presented. In the new scheme, we sample the structure of the solute molecule and solvent molecules separately. First, we execute a QM/MM MD simulation, where we sample the solute molecule in solution. Next, we choose random solute structures from this simulation and perform classical MD simulation for each chosen solute structure with its geometry fixed. This new scheme allows us to sample the solute molecule quantum mechanically and sample many solvent structures. This scheme is combined with the generalized-multiconfigurational perturbation theory and applied to study the absorption spectra of Coumarin 120 in water. We succeeded in constructing the absorption spectra and in realizing the red shift of the absorption spectra found in polar solvents. We found that the umbrella-like open-close motion of the amino group of the coumarin plays an important role in the broadening of the spectra, whereas the red shift of the peak was caused by the solvation structure of the amino group.