We investigate the transformation from ordinary gauge field to noncommutative one which was introduced by N. Seiberg and E. Witten (hep-th/9908142). It is shown that the general transformation which is determined only by gauge equivalence has a path dependence in `θ-space'. This ambiguity is negligible when we compare the ordinary Dirac-Born-Infeld action with the noncommutative one in the U(1) case, because of the U(1) nature and slowly varying field approximation. However, in general, in the higher derivative approximation or in the U(N) case, the ambiguity cannot be neglected due to its noncommutative structure. This ambiguity corresponds to the degrees of freedom of field redefinition.