This paper presents the results for a sensitivity analysis of the time/depth dependent chloride diffusion model in concrete using differential analysis techniques. Four governing parameters of the model are taken to determine the sensitivity of the chloride diffusion coefficient: the time of exposure, inspecting depth, surface chloride concentration, and chloride concentration at the inspecting point. The results of this sensitivity analysis are discussed in detail, including variations in the diffusion coefficient according to the four parameters and the implications for durability design of concrete structures.