  Possible $CP$-violation in top-quark couplings is discussed. It is shown that
the lepton-energy distributions in $e^+ e^- \to t\bar{t} \to \ell^+\ell^-X /
\ell^\pm X$ at next linear colliders (NLC) could give us useful information for
this study. The statistical significance of $CP$-violating-parameter
determination is estimated.
