Deviations from the standard Higgs sector generated by some new physics at an energy scale $Lambda$ could be described by an effective $SU(3)_c times SU(2)_L times U(1)$ invariant non-renormalizable Lagrangian terms of dimension six. A systematic study of various Higgs boson production channels ($gamma gamma$, $ZZ$, $WW$, $b bar b$, $tau bar tau$) at the International Linear Collider (ILC) in the SM extension by effective operators is carried out. Statistical methods are used to establish a degree of consistency for the standard Higgs sector with the forthcoming data, using the expected ILC accuracies of the Higgs boson production channels. Global fits in the two-parametric anomalous coupling space indicating to possible deviations from the standard Higgs-fermion and Higgs-gauge boson couplings are performed.