  Electric dipole moments (EDMs) of nucleons and nuclei are actively considered
as direct evidence of the CP violation. Calculations of nucleon EDMs on lattice
are required to connect the quark- and hadron- level effective CP violating
interactions within QCD or other CP violating sources in new physics beyond the
standard model. Among them, the theta-induced nucleon EDM, that is the only
such renormalizable interaction, has widely been investigated on a lattice. In
the report, we review recent developments of the lattice calculations of
nucleon EDM induced QCD theta term.
