Undagi is a term for traditional Balinese architects. An undagi equips himself with engineering knowledge and has to learn and understand art, culture, customs, and religion. This must be mastered by an undagi so that designing and creating building works is in harmony and line with the concept of Asta Kosala Kosali Bali. The role of an undagi in designing traditional buildings and sacred buildings is critical because it involves nature, humans, and God. This causes an undagi to be holy because it has to be in direct contact with God. The role of Undagi in Traditional Architecture is significant and big because an undagi has noble values that can influence the development and order of life of traditional Balinese people from time to time. The phenomenon that occurs in the present era is the degradation of Undagi's role which is faced with the challenges of modernization in terms of concepts, technology, materials and modern style forms. This study will investigate the extent to which Undagi's role in developing traditional Balinese architecture based on Asta Kosala Kosali is and how the Undagi's role is in the development of traditional Balinese architecture in the contemporary era with the influence of modernization and globalization. The research was conducted using a qualitative method, namely through in-depth interviews with the snow ball method to the Undagi, traditional leaders and the community as well as direct observation of the work of the Undagi on traditional Balinese architecture to obtain information on the role of Undagi and the resilience of Undagi in the present. This study indicates a decline in the transfer of skills and knowledge of the Undagi to the next generation. Therefore, this study's results are expected to contribute to science, namely how the resilience of Undagi's role as Balinese local wisdom in preserving the sustainability of Balinese Traditional Architecture development.