The most important goal of records management is to document the administrative responsibility of the institution producing records and its history. For this purpose, each institution needs to make a plan determining kind and value of phenomena and evidences to be documented, that is, a plan for documentation. This study was aimed to present its necessity and stretagy, focussing on the documentation of correlations with external factors surrounding National Assembly (external relations). Through literature survey, external relation functions of congress and important sources associated with their functions were analyzed. and what records were produced from those sources was investigated in the case of U.S. Congress. Comparing with the present state of National Assembly on this basis, four significant subjects to activate the external relations documentation plan in the point of institutional policy of National Assembly were proposed : legislation of documentation program of external relations, acquisition policy, advocacy enforcement for National Assembly Documentation, and establishment of cooperation and support systems with external factors.