The Agency for Defense Development (ADD) was established in August 1970 as part of an effort to achieve reliable self-defense capabilities. ADD is the one and only national agency that engages in defense technology R&D in support of national defense and improving overall national R&D capabilities and fostering domestic industrial development. When ADD was established, it seemed impossible that South Korea would be able to manufacture even basic weapons, but it now produces some of the most advanced weapon systems in the world, placing South Korea 10th in global defense technology production. However, ADD has had to adjust to rapidly changing security and R&D environments, the key to which has been innovation. ADD is transforming into a customer-oriented agency that develops core weapon systems and highly advanced technologies. In order to do so, we need to understand what societies and militaries require. We are also becoming more open in our cooperation with our R&D partners, namely industries, academia, research institutes, and the military. ADD will do its best to become a world-leading R&D agency.