Stunting is a chronic nutritional problem that occurs in toddlers, defined based on height for age (TB/U) which is less than two negative standard deviations or a toddler's height is shorter than it should be. Stunting is a chronic nutritional problem in toddlers, characterized by a shorter height than the height of children his age. Bulungan Regency is one of 160 urban regencies in Indonesia that is intervened to focus on reducing stunting. Based on these problems, this study aims to determine the cluster of stunting vulnerabilities in Bulungan Regency. The method used is Fuzzy C-Means (FCM). The results of this study are that the area in cluster 1 has a high level of vulnerability because it has the lowest level of adequacy of posyandu (active) and high incidence of LBW in infants, cluster 2 has a moderate level of vulnerability because it has an adequate level of puskesmas, adequacy of posyandu (active), the adequacy of doctors, the adequacy of nutritionists, the adequacy of midwives, the percentage of moderate LBW, and cluster 3 have a low level of vulnerability because they have a low average percentage of LBW and a high level of adequacy of posyandu (active) in the area.