The Area-Based Management Tool (ABMT) is a tool used for marine environmental management. The International Seabed Authority (ISA), which manages mineral resources beyond the national jurisdiction, also uses the ABMT for marine environmental management. The ISA uses two types of ABMTs: one for environmental impact assessment (EIA) and one for environmental conservation. The former has its roots in a resolution of the International Union for Conservation of Nature (IUCN) in 1979 and is carried over into the ISA exploration regulations and the Recommendations for the guidance of contractors for the assessment of the possible environmental impacts arising from exploration for polymetallic nodules in the Area. The latter originated as a proposal from the National Research Council (NRC) in 1984 and is the basis for the Regional Environmental Management Plan (REMP). However, the two have had issues such as overlapping names and diversifying purposes since their inception, which remain unresolved to this day. Therefore, this chapter examines the history of ABMT in relation to deep seabed mineral resource development, clarifies how the above-mentioned issues arose, and provides basic information for future organization.