  We have revisited the calculation of the neutron electric dipole moment in
the presence of the CP-violating operators up to dimension five based on the
chiral perturbation theory. Especially, we focus on the contribution of
strangeness content. In the calculation, we extract the nucleon matrix elements
of scalar-type quark operators from the results of the lattice QCD simulations,
while those of the dipole-type quark-gluon operators are evaluated by using the
method of the QCD sum rules. As a result, it is found that although the
strangeness quantity in nucleon is small, the contribution of the
chromoelectric dipole moment of strange quark may be still sizable, and thus
may offer a sensitive probe for the CP-violating interactions in physics beyond
the Standard Model.
