Nitrogen (N) provides great benefits as a fertilizer for food production and as a material for industrial production. However, its use simultaneously induces N pollution, which threatens the health of human beings and ecosystems due to low N use efficiency in the anthroposphere. This is the N issue—a tradeoff between large benefits and threats. It is our responsibility to have future generations inherit sustainable N use by resolving the N issue. Groundwater nitrate pollution is a form of N pollution that should be addressed to prevent harm to human and animal health through drinking water and aquatic ecosystems through excess eutrophication. Links between groundwater nitrate pollution in N cycling and the N issue are reviewed to provide information for international and domestic actors to address the N issue, and to indicate groundwater nitrate pollution research needed to comprehensively address the N issue. Concretely, global and local N cycling and links with groundwater N processes are overviewed. The status of the N issue is summarized and a comprehensive framework to grasp the entire issue is introduced, i.e., the driver–pressure–state–impact–response (DPSIR) framework. Programs and projects tackling the N issue in Japan and around the world are summarized. Research required on groundwater nitrate pollution that contributes to resolving the N issue is discussed, and future expectations are indicated.
