In this paper, an analytical solution is presented for magnetic shielding analysis of a slit on a conducting plate coated with a ferrite sheet. The Fourier transform and the mode matching technique are employed to obtain the analytical solution for magnetic vector potential. Magnetic shielding effectiveness is investigated in terms of the geometrical parameters of a slit on a conducting plate and a ferrite sheet. The proposed method is numerically validated by a commercial finite element solver with good agreement. In addition, the proposed analytical solution is in a rapidly converging series so that it is more efficient than other numerical techniques.