In this work, a derivative of spectrum of polarization resonances in 5S 1/2 -5D 5/2 transitions of Rb atoms at different values of longitudinal magnetic field, which occurs due to the Faraday effect, was observed in a temperature controlled and magnetically shielded cell. The amplitude and spectral shape of Faraday resonances were investigated as a function of external magnetic field and the experimental results are described by a simple theoretical model.