  We describe the phenomenon of optical activity of noncentrosymmetric metals
in their normal and superconducting states. The found conductivity tensor
contains the linear in wave vector off diagonal part responsible for the
natural optical activity. Its value is expressed through the ratio of light
frequency to the band splitting due to the spin-orbit interaction. The Kerr
rotation of polarization of light reflected from the metal surface is
calculated.
  In the additional file "Erratum" I've pointed out the sign error in
arXiv:1001.2113 ( PRB v.81, 094525 (2010)) that leads to the wrong statement
about the Kerr effect in light reflection from the surface of media without
space parity.
