For nose-whistler extrapolation at high latitudes, many successful methods have been developed. However, in regard to nose-whistler extrapolation at low or medium-low latitudes, the formulae for high latitudes cannot be used because of the complicated situaton and the unsatisfactory approximation used. A new method proposed in this paper includes the case of high latitudes as a specific case, and, in particular, can be used for the case of low latitudes. We can say that this method is a generalization of the old methods used before.