This paper describes a method of computer simulation on the processes of exposure and development in a photographic material. The method described by the authors is based on a mathematical model for the transfer gradient characteristics of photographic layer which was examined preliminary. On the numerical analysis of parameters utilized in the mathematical model, a set of characteristics curves which were obtained by experiment was adapted. For the computer simulation on the processes of exposure and development in a photographic layer model, the Monte Carlo method was employed. The rationality of this computer simulation method was confirmed by comparing the characteristics curves which were generated by this method and those of obtained by experimentally.