  On the basis of a seesaw-type mass matrix model for quarks and leptons, $M_f
\simeq m_L M_F^{-1} m_R$, where $m_L\propto m_R$ are universal for $f=u,d,\nu$
and $e$ (up-quark-, down-quark-, neutrino- and charged lepton-sectors), and
$M_F$ has a form [(unit matrix)+(democratic-type matrix)], neutrino masses and
mixings are investigated. It is tried to understand a large
$\nu_\mu$-$\nu_\tau$ mixing, i.e., $\sin^2 2\theta_{23}\sim 1$, with $m_{\nu 1}
\ll m_{\nu 2} \sim m_{\nu 3}$, which has been suggested by the atmospheric
neutrino data.
