The enthalpies of transfer of ethanol from aqueous to aqueous α- or β-cyclodextrin (CD) solutions have been determined by microcalorimetry at various mole fraction at 298.15 K. The molar enthalpy of ethanol with α-CD was negative, whereas that with the α-CD system was positive. In order to clarify the major contribution of the interaction energy of CD's and guest molecules, the dispersion energies were determined using dispersion-corrected density functional theory calculations. In the case of α-CD, the dispersion energies increase with an increase in the number of carbon atoms of the guest molecule.