In the field of historical study, the system called Digital Archive, which digitizes historical resources and publish them on the web, has been developed. This helps preventing damage of resources and providing them beyond temporal and geographical constraints. On the other hand, practical use of Digital Archive has not been considered, because the primary aim of it is preservation and publishing of them. This prevents from sharing data and knowledge with others and efficient usage of published data such as digitalized images and catalog data. As for this problem, Linked Data has been considered as one of solutions. Linked Data is a term used to describe a practice for sharing and connecting data and knowledge on the web. The objective of this paper is to develop the system to support knowledge discovery in historical study by use of Linked Data. Developed system connects with Digital Archive through Linked Data, and allowed historians to use catalog data on the web and research data, which historians accumulate based on their objectives, integrally. This helps historians to analyze a large amount of historical resources quantitatively, and encourages to discover new knowledge which have not been discovered by qualitative analysis. We apply developed system to the case of historical study, and the effectiveness was verified by finding new characteristics of historical resources.