It is important for both the estimation of geothermal energy potential and the exploraton of geothermal energy to have the rough information relating the temperature distribution of the lower crust or the upper mantle. Recently, Curie point method, which gives the Curie isotherm suface through the analysis of aero maanetic data, is thought to be one of the remarkable techniques for this purpose. Curie point method is devided into two in technically, i, e., i) spectral approach, ii) model simulation approach. Interactive software has found to be useful through the model experiments especially. The model simulation approach software has been applied to the aeromagnetic data across the island arcs and it was found that the resultant Curie isotherm surface had fairly good correspondence with the result which derived from the analysis of heat flow data.