  The Hubbard model with additional intersite interaction `$V$' (the extended
Hubbard model) is investigated by the correlator projection method (CPM). CPM
is a newly developed numerical method which combines the equation-of-motion
approach and the dynamical mean-field theory. Using this method, properties of
the extended Hubbard Model at quarter filling are discussed with special
emphasis on the metal-insulator transition induced by electron-electron
correlations. The result shows a metal-insulator transition to a charge ordered
insulator with antiferromagnetic order at low temperatures, but a charge
ordered insulator without magnetic symmetry breaking at intermediate
temperatures. Here, the magnetic order is found to be suppressed to low
temperatures because of the smallness of the exchange coupling $J_{\rm eff}$.
The present results are in sharp contrast with the Hatree-Fock approximation
whereas in agreement with the experimental results on quarter-filled materials
with strong correlations, such as organic conductors.
