Natural rubber, primarily derived from Hevea brasiliensis, is a critical resource for a sustainable society due to its unique properties and indispensable applications in industries such as tire manufacturing, medical supplies, and industrial components. As the global demand for natural rubber continues to rise, ensuring the stability of its supply is increasingly important. However, H. brasiliensis faces significant threats due to its reliance on clonal propagation and diseases such as leaf-fall disease, which jeopardize supply security. To protect natural rubber as a genetic resource, long-term efforts are required to enhance resistance to leaf-fall disease, alongside breeding and conservation initiatives. Additionally, the conservation of rubber trees not only ensures sustainability but also strengthens local economies that depend on rubber cultivation. This chapter discusses the current status of natural rubber supply and H. brasiliensis cultivation, the challenges posed by leaf-fall disease, and our approach to these issues through scientific and integrated methods. By conducting innovative research and taking proactive actions, we aim to secure the long-term sustainability of the natural rubber industry while addressing environmental, economic, and social challenges.