A method for automatically generating by use of a computer a simulation program for simulating a phenomenon in a region by discretizing automatically data of a partial differential equation inputted when the partial differential equation and boundary conditions governing the phenomenon and data representing the shape of a region, which is an object of calculation, are given, by using a discretization rule by the finite differential method, and for generating a program calculating numerical values representative of the phenomenon determined by the partial differential equation over the whole object region of calculation by the finite differential method on the basis of the equation after the discretization, wherein the object region of calculation is divided into a plurality of blocks, each of which has the same differential equation and the same discretization rule and a program is generated which calculates, for each of the blocks numerical values representative of the phenomenon determined by the partial differential equation and the discretization rule both applied for each of the blocks by the finite differential method.