In this study transverse magneto-optical Kerr effect in transmission for the magnetite thin film with gold grating on top was examined theoretically and experimentally. The magnetite films with thickness of 200 nm were fabricated by the laser electrodispersion technique. Arrays of gold stripes with 600 nm period and 350 nm and 500 nm stripe widths were created by lift-off e-beam lithography. It was shown experimentally that the TMOKE enhancement in structures with 350 nm width is attributed to SPP excitation on gold-magnetite
surface. TMOKE value δ reaches magnitude of ±5∙10-3 at the wavelengths 790 nm and 860 nm at light incidence angles of 8-10° and 12-13°, respectively. In case of 500 nm stripe width, SPP excitation is poor, however δ reaches magnitude of ±6.6∙10-3 at angles of incidence more than 20°, that can be associated with the quasiguided mode resonance in such structure.