Chemical properties of benzene molecules adsorbed on the hydroxyl, H+ and Na+ sites of Y-zeolite surfaces were investigated by using UV absorption and FT-IR spectroscopies. The analyses on the IR peaks assigned to a C–H out-of-plane vibration mode revealed two different adsorption states of benzene: (1) a benzene molecule located a little distance from the hydroxyl groups of zeolite inner walls, and (2) a benzene molecule positioned a short distance from the H+ or Na+ sites of zeolite walls. Furthermore, the electronic properties of benzene molecules adsorbed on these Y-zeolites were investigated by UV absorption measurements. The vibrational splitting in UV absorption spectra of benzene provided the information about IR-inactive skeletal vibrations of the benzene ring, such as C–C–C in-plane bending and breathing modes. The benzene molecules strongly interacting with H+ or Na+ sites of Y-zeolites showed smaller breathing vibration energy as compared to benzene in gas or liquid phases, clearly indicating the stabilization of the benzene ring. In contrast, the benzene molecules weakly interacting with hydroxyl groups of siliceous USY zeolite were barely stabilized.