Nitrogen (N) deposition has increased dramatically worldwide, which may affect forest soils in various ways. In this study, we conducted a short-term manipulation experiment of N addition on two types of forest soils (urban and rural soils) found in Korea. N addition significantly decreased phenol oxidase activities in urban soil samples; however, it did not affect those in rural soils. Furthermore, N addition did not change ${eta}$-glucosidase and N-acetylglucosaminidase activities, except for ${eta}$-glucosidase activities in the O layer of rural soils. Changes in microbial biomass and general activity (dehydrogenase activity) were not induced by N addition, except for dehydrogenase in the A layer of urban soils. Although N addition did not change the extractable soil nutrients, organic matter, and water contents significantly, it enhanced nutrient leaching and resulted in lower pH leachate. These results suggest that excessive N addition to forest soils may induce nutrient leaching in the long-term. Overall results of our study also suggest that N addition may induce retardation of organic matter decomposition in soils; however, such a response may depend on the intensity of previous exposure to N deposition.