  The process of top quark pair production at Next Linear Collider (NLC) has
been considered adopting an effective Lagrangian approach and including all
operators of dim~6 which can be tree-level-generated within unknown underlying
theory. All contributing helicity amplitudes are presented. It has been found
that four-fermion operators can provide the leading non-standard contribution
to the total cross section. Expected statistical significance of the
non-standard signal for the total cross section and forward-backward asymmetry
have been calculated taking into account existing experimental constraints. It
has been shown that adopting realistic luminosity of NLC and conservative
efficiency for the top-quark pair detection, the total cross section may be
sensitive to non-standard physics of an energy scale around $\Lambda=5\tev$.
