This chapter discusses the relationship between climate security and human security, focusing on how Japan can effectively integrate climate change measures into its broader security policies. Climate security, a concept increasingly recognized in international discourse, highlights the risks climate change poses to sociopolitical stability, such as exacerbating conflicts and causing socioeconomic disruptions. These issues are linked to human security, which emphasizes protecting people’s fundamental livelihoods, rights, and freedoms. This chapter argues that climate security and human security are interdependent: the impacts of climate change undermine human security by threatening livelihoods, health, and safety. Constrained by its pacifist constitution, Japan has not fully embraced climate security in its national policy despite the increasing international focus on the topic. The chapter proposes that Japan adopt a “human security” lens to address climate challenges, aligning its foreign and domestic policies with global climate security efforts. This approach emphasizes nonmilitary means of addressing climate threats, fostering international cooperation, and enhancing social resilience.