  We impose $O(3)_L\times O(3)_R$ flavor symmetry in the supersymmetric
standard model. Three lepton doublets $\ell_i$ transform as an $O(3)_L$ triplet
and three charged leptons $\bar e_i$ as an $O(3)_R$ triplet, while Higgs
doublets $H$ and $\bar H$ are $O(3)_L\times O(3)_R$ singlets. We discuss a
flavor $O(3)_L\times O(3)_R$ breaking mechanism that leads to "successful"
phenomenological mass matrices, so-called "democratic" ones, in which the large
$\n_\mu-\n_\tau$ mixing is naturally obtained. Three neutrinos have nearly
degenerate masses of order $0.1\eV$ which may be accesible to future double
$\b$-decay experiments. We extend our approach to the quark sector and show
that it is well consistent with the observed quark mass hierarchies and the CKM
matrix elements. However, the large mass of the top quark requires a relatively
large coupling. constant.
