  We investigate the SO(10) grand unified model with generation flipping. The
model contains one extra matter multiplet $\psi(10)$ and it mixes with the
usual matter multiplets $\psi_i(16)$ when the SO(10) is broken down to SU(5).
We find the parameter region of the model in which the observed quark masses
and mixings are well reproduced. The resulting parameter region is consistent
with the observation that only $\psi_i(16)$ have a source of hierarchies and
indicates that the mixing between second and third generations tends to be
large in the lepton sector, which is consistent with the observed maximal
mixing of the atmospheric neutrino oscillation. We also show that the model can
accommodate MSW and vacuum oscillation solutions to the solar neutrino deficit
depending on the form of the Majorana mass matrix for the right-handed
neutrinos.
