We conducted a theoretical study on magneto-optical (MO) properties of cylindrical metallic nanowires. The MO conductivity was calculated using the Kubo formula. Results show that in contrast to parabolically confined quantum wires realized from low-dimensional semiconductor systems, the features of MO absorption and the retard effect of the MO response by cylindrical metallic nanowires depend sensitively on the polarization of the radiation field due to corresponding selection rules. The frequencies of resonant absorption induced by inter-subband MO transition channels are within the terahertz (THz) bandwidth and can be tuned effectively by adjusting the radius of the nanowire and/or varying the strength of the magnetic field. This study is pertinent to the potential application of metallic nanowires as frequency-tunable THz optoelectronic devices