We have fabricated a highly crystalline thin film of indium tin oxide (ITO) to examine the relationship between properties of charge carriers and their collective plasmonic response. The ITO thin film with atomically flat surface was epitaxially grown on a yittria-stabilized zirconia substrate by using pulsed laser deposition. Attenuated total reflectance spectra for the infrared (IR) region in the Otto configuration show a dip for p-polarized light, corresponding to an excitation of surface plasmon polaritons. The IR reflectivity data can be well reproduced by the theoretical calculation based on the Fresnel model, in which the dielectric function of ITO is deduced from the Drude theory using the carrier density and mobility obtained by Hall measurement. The high carrier mobility in single crystalline ITO thin film is found to result in a significantly low optical loss in the IR region. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim