  We study the neutron electric dipole moment in the presence of the
CP-violating operators up to the dimension five in terms of the QCD sum rules.
It is found that the OPE calculation is robust when exploiting a particular
interpolating field for neutron, while there exist some uncertainties on the
phenomenological side. By using input parameters obtained from the lattice
calculation, we derive a conservative limit for the contributions of the CP
violating operators. We also show the detail of the derivation of the sum
rules.
