Although the studies of tensor structure of the Higgs boson interactions with vector bosons and fermions at CMS and ATLAS experiments have established that the JPC quantum numbers of the Higgs boson should be 0++, small CP violation in the Higgs sector (i.e. contribution of the CP-odd state of 10% or less) cannot be excluded with the current experimental precision. We review a possibility to measure the CP violating mixing angle between scalar and pseudoscalar states of the extended Higgs sector, at 1 TeV ILC with the ILD detector.