The A-, B-, and C-absorption band shapes due to the cation vacancy nearby as well as the electron-lattice interaction have been systematically investigated by using the Monte-Carlo simulation for <Sn>^<2+> and <Pb>^<2+> in alkali halide crystals. Not only the cation vacancy located at the nearest-neighbour to the impurity ion but also one at the next nearest-neighbour were taken into account in calculation. Temperature dependence of spectra has also been examined.