We study the nature of the top-Higgs flavor changing neutral current (FCNC) couplings in the
$t\bar t$ production at polarized linear colliders. We show how the polarized linear colliders can be
used to determine the chirality of the FCNC coupling by using the angular distributions of the top
decay products and by examining relevant asymmetries along with the top spin polarizations and
correlations. We obtain a limit on the couplings and find the 3σ upper bound on BR(t → qH) <
8.84×10−4 a%t √s = 500 GeV and L = 500 fb−1.