  Formation of a neutron star is accompanied by neutrino emission carring about
10% of the rest energy of the star. Toroidal field produced by twisting of a
dipole field in differentially rotating star is antisymmetric. Its summation
with antisymmetric toroidal field results in braking of mirror symmetry of the
magnetic field . For large magnetic field the neutron decay rate depends on its
strength. Neutrino is emitted more in one direction leading to flux asymmetry
and recoil of the neutron star. Estimations show that the neutron star can
reach velocities $\sim 1000$ km/s for 3% asymmetry of the neutrino flux.
