  We study radiative activity of magnetic white dwarf undergoing torsional
vibrations about axis of its own dipole magnetic moment under the action of
Lorentz restoring force. It is shown that pulsating white dwarf can convert its
vibration energy into the energy of magneto-dipole emission, oscillating with
the frequency equal to the frequency of Alfv\'en torsional vibrations, provided
that internal magnetic field is decayed. The most conspicuous feature of the
vibration energy powered radiation in question is the lengthening of periods of
oscillating emission; the rate of period elongation is determined by the rate
magnetic field decay.
