  Energies of symmetric nuclear matter and neutron matter are evaluated in the
lowest order Bruekner theory using the Ch-EFT potential including effects of
the three-nucleon force (3NF). The 3NF is first reduced to density-dependent
nucleon-nucleon (NN) force by folding single-nucleon degrees of freedom in
infinite matter. Adding the reduced NN force to the initial NN force and
applying a partial-wave expansion, we perform $G$-matrix calculations in pure
neutron matter as well as in symmetric nuclear. We obtain the saturation curve
which is close to the empirical one. It is explicitly shown that the
cutoff-energy dependence of the calculated energies is substantially reduced by
including the 3NF. Characters of the 3NF contributions in separate spin and
isospin channels are discussed. Calculated energies of the neutron matter are
very similar to those used in the literature for considering neutron star
properties.
