Historical maps are precious materials which show spatial distribution of land use, streets and so on at the time when the maps were produced. In analysis of historical maps, the most primitive and comprehensive method is to compare them directly with the present ones by overlaying. However, the low precision, in the geometrical sense, of the historical maps makes the task of comparison very difficult. This paper proposes an effective geometric correction method in which Triangulated Irregular Network (TIN) model and Affine transformation are employed. This paper also shows some applications which illustrate the significance of the geometric correction of historical maps.