Background  This study explored the association of residence, caste, social determinants of health (SDH) of parents, and daily junk food intake with the nutritional status of school children living in different residential areas of a district in Nepal. Methods  A survey was conducted from December 2017 to March 2019, including 331 school children aged 6 to 12 years as well as their parents, in the primary village for Japan International Cooperation Agency (JICA) support and the surrounding area in the Machapuchare Administrative Region of Kaski District, Gandagi Province, Nepal. In this study, the body mass index for age z-score (BMIZ), a criterion used by the WHO for assessing malnutrition, was used for determining underweight; BMIZ <−2 SD was defined as underweight.  The children’s anthropometric data were measured to assess their nutritional status, and a survey on children’s daily junk food intake and parents' SDH was conducted among parents. The responses were analyzed by logistic regression analysis.Results  Of the children who participated in the survey, 31 (9.4%) were underweight.   An association between parents’ SDH and children’s underweight was found after adjusting for mothers’ age at marriage, number of siblings, and daily junk food intake, and the results showed that lower caste (OR＝0.241, p＝0.001), lower education of mothers (OR＝3.879, p＝0.011) and non-literacy of fathers (OR＝2.790, p＝0.023) had statistically significant effects on BMIZ.Conclusions  In this study, BMIZ, indicating underweight in Nepalese school children, was associated with higher caste and a mother’s level of educational attainment and father’s of non-literacy. To understand the factors influencing children’s health, it is necessary to evaluate sociodemographic parameters of parents as childcare providers, including culture, education, employment, living conditions, and diet, and to conduct surveys that capture data on the SDH of parents from various perspectives.