  Analysis of polarimetric observations of X-ray binary Cyg X-1/HDE 226868
including the data obtained by BTA-6m allows to estimate the magnetic field
magnitude near the inner radius of the accretion disk. The magnetic field
magnitude occurred to be $\sim 10^{8}$ G. For power law of radial dependence of
magnetic field into an accretion disk we estimates the value of an index of
power law. For the Cyg X-1/HDE 226868 system the value of this index appears
non less then two. If one accepts as a characteristic scale of a magnetic field
generation region the dyadosphere radius, one can estimate the charge magnitude
of a black hole. For Cyg X-1 this magnitude appears to be $\sim 0.01M\sqrt{G}$,
where M is a black hole mass.
