We present a feasibility study of the muon polarization measurement to extract the Michel parameter $\xi'$ in $\tau$-decays. We suggest as a method using the angular distribution of an electron in the rest frame of a decayed in the drift chamber muon, as electron momentum correlates with muon polarization. The Monte Carlo simulation of the Belle detector with parameters of the Future Super charm-tau Factory beams was used to generate signal events. The possible background was studied and methods of its suppression were suggested. The most contribution is expected from the light mesons decays-in-flight and particles scattering. The reconstruction efficiency and statistical uncertainties were estimated.