CP-Violating Lepton-Energy Correlation in e\bar{e}\to t\bar{t}

In order to observe a signal of possible CP violation in top-quark couplings, we have studied energy correlation of the final leptons in $e^+e^-\to t\bar{t}\to \ell^+\ell^-X/\ell^\pm X$ at future linear colliders. Applying the recently proposed optimal method, we have compared the statistical significances of CP-violation-parameter determination using single- and double-lepton distributions. We have found that the single-lepton distribution analysis is more advantageous.