Grinding is one of the machining methods for finishing that is performed by using a large number of abrasive grains with irregular shapes and random distribution. While this feature enables accurate and high-quality machining, it complicates analysis of the grinding process. To solve this problem, a great number of computer simulations have been carried out using the Monte Carlo method. Most of them, however, statically calculate geometric interaction between a grain and a workpiece, and have not provided enough achievements for practical applications. In this study, taking this background into account, a simulation program has been developed based on the elastic support model of a grain in which the elasticity of grain support changes according to its location. The program focuses on the generation process of a workpiece surface, and simulates the interaction between grains and a workpiece, which includes the elastic and plastic deformation as well as the removal of workpiece material. Examples of the simulation shown in this study verify the fact that the simulation program facilitates analysis of the microscopic grinding phenomena, and can be used as a practical tool for predicting the grinding results and for optimizing grinding parameters.