The local refinement technique is very useful method to get high-precision solution with lower efforts in the structural grid system and has been applied to many cases. In using this method, some methods are needed to specify the regions on which the mesh should be fined on the calculation domain and a method based on the truncation error estimation theory was proposed. This method makes it possible to determine the regions with only one, non-iterative calculation and is useful for implicit method. A local mesh refinement method with SIMPLE algorithm was applied to the abovementioned region. This method basically satisfies the conservation law on the fine/coarse cell boundaries. As a result, high-precision solution was got with shorter time and smaller memory in comparison with the usual method.