  We study a mechanism where tiny neutrino masses arise only from radiative
contribution in a supersymmetric model. In each generation, the tree-level
light neutrino mass is rotated away by introducing a second SM singlet $s_{L}$
that forms a Dirac mass term with the right-handed neutrino $n_{R}$. Even with
non-zero Majorana neutrino mass for the right-handed neutrinos $M_{R}
\bar{n^{c}_{R}} n_{R}$, the lightest neutrino remains massless at tree level
due to an approximate symmetry as $U(1)_{\nu-s}$. Holomorphic feature of
superpotential ensures that the Majorana neutrino masses $M_{R} \bar{n^{c}_{R}}
n_{R}$ and $M^{*}_{R} \bar{s^{c}_{L}} s_{L}$ are not generated simultaneously.
However, the $U(1)_{\nu-s}$ is not respected by the SM gauge interactions or
interaction with Higgs. Consequently, tiny neutrino masses arise from radiative
contributions. It is also shown that the right-handed neutrino Majorana mass
$M_{R}$ can be at $\cal O$(KeV) to obtain the proper light neutrino mass.
