Nanodisk array with sandwich structure of Au/[Co/Pt]n/Au was fabricated by electron beam lithography combined with argon ion milling. Excitation of localized surface plasmon resonance (LSPR) was demonstrated for various disk diameters. Magneto-optical (MO) properties were measured by a home-made micro-Faraday system at wavelengths of 633 and 690 nm. Faraday ellipticity at 690 nm showed non-monotonic dependence on disk diameter and reached maximum for disk diameter of 84 nm, which was associated with LSPR at 690 nm. The experimental results show direct evidence for LSPR enhancement effect on MO properties. The optical and MO properties were fitted by average field approximation.