  The top quark mass and the flavor mixing are studied in the context of a
Seesaw model of Quark Masses based on the gauge group $SU(2)_L \times SU(2)_R
\times U(1)$. Six isosinglet quarks are introduced to give rise to the mass
hierarchy of ordinary quarks. In this scheme, we reexamine a mechanism for the
generation of the top quark mass. It is shown that, in order to prevent the
Seesaw mechanism to act for the top quark, the mass parameter of its isosinglet
partner must be much smaller than the breaking scale of $SU(2)_R$. As a result
the fourth lightest up quark must have a mass of the order of the breaking
scale of $SU(2)_R$, and a large mixing between the right-handed top quark and
its singlet partner occurs. We also show that this mechanism is compatible with
the mass spectrum of light quarks and their flavor mixing.
