Effects of electromagnetic retardation on the rupture process of a very thin liquid film coated on a flat plate are studied. The analysis results indicate that the electromagnetic retardation effect (D) for the case A > 0 (attraction) is a stabilization factor, which prolongs the rupture time. The wavenumber of the most unstable mode is decreasing as D increases. It is also found that the linear solution of rupture time T-LM is larger than the nonlinear rupture time T-NM, but the gradient of T-LM to D is comparable to that of TNM.