  The root-mean square radius of the deuteron magnetic moment distribution, $
r_{Md}$, is calculated for several realistic models of the $NN$--interaction.
For the Paris potential the result is $r_{Md} = 2.312 \pm 0.010 $ fm. The
dependence of $r_{Md} $ on the choice of $NN$ model, relativistic effects and
meson exchange currents is investigated. The experimental value of $r_{Md}$ is
also considered. The necessity of new precise measurements of the deuteron
magnetic form factor at low values of $Q^2$ is stressed.
