Absorption spectra were observed for several Ho(III)-ligand systems in aqueous solution under the changes of ligand concentration and temperature. The intensity change of hypersensitive band $(^5I_8; o;^5G_6)$ was quite remarkable with temperature and concentration, and was interpreted as the change of coordination environments. The transition intensities observed in these spectra were analyzed in terms of the Judd-Ofelt intensity parameters, $Omega_lambda$ ($lambda$ = 2, 4, 6), for 4f $ o$ 4f electric dipole transitions. The $Omega_2$ parameter was the most sensitive to the temperature and concentration. Using the changes of $Omega_2$, $Cl^-$ and ${NO_3}^-$ ions were found to form inner sphere complexes in aqueous solution.