Nursing Mouth Caries (NMC) is a caries lesion with unique pattern in infants, toddlers, and preschool children which caused by the provision of formula milk, breastmilk or other sweet liquid in a long period. Dental caries is still one of the most frequent problems occur in Indonesia society, not only in adults but also in children. Purpose: The aims of this research are to investigate how the NMC level which is seen from the age of the child, the habits of child's feeding and toothbrushing, and also their mother's level of education and knowledge. Methods: This research used a purely descriptive method. Data taken by purposive sampling of 100 children aged 2-5 years old with interview procedures on the child's mother and child clinical examination of the oral cavity. Results: The results of this research was high level NMC which reached 96%, seen from the age of the child, the habits of child's feeding and toothbrushing, and mother's level of education and knowledge. Conclusion: Based on conducted research, it can be concluded that lacking of mother's knowledge of children's oral health was causing high rates of NMC. The higher the age of the child, tend to be higher rates of NMC expansion that occurs in children. The children who drank formula milk have the greater risk on NMC than children only drank breast milk exclusively. Children brushing habits were also contribute in the formation of the NMC, while the level of education of the mother allegedly did not much contribute in the occurrence of NMC in children. Keywords: NMC, breastmilk, formula milk, rate of accidence.