The process of top quark pair production at Next Linear Collider (NLC)
has been considered adopting an effective Lagrangian approach and inc
luding all operators of dim 6 which can be tree-level-generated within
unknown underlying theory. All contributing helicity amplitudes are p
resented. It has been found that four-fermion operators can provide th
e leading non-standard contribution to the total cross section. Expect
ed statistical significance of the non-standard signal for the total c
ross section and forward-backward asymmetry have been calculated takin
g into account existing experimental constraints. It has been shown th
at adopting realistic luminosity of NLC and conservative efficiency fo
r the top-quark pair detection, the total cross section may be sensiti
ve to non-standard physics of an energy scale around Delta = 5 TeV.