The purpose of this study was to explore how social support, mother's psychological status, and maternal sensitivity affected attachment security in children with disabilities by using the structural equation model (SEM). Subjects were 141 pairs of children with disabilities and theirs mothers. Empirical data was obtained through a series of questionnaires such as marital satisfaction, support from people around, maternal depression, and parenting stress. In addition, maternal sensitivity and attachment security were obtained through a Maternal Behavior Q-set and an Attachment Behavior Q-set. The results were as follows: first, mother's psychological status was fully mediated by social support and maternal sensitivity. Secondly, mother's psychological status had a negative effect on maternal sensitivity, while her maternal sensitivity, in turn, had a positive effect on the child's attachment security. However, maternal sensitivity did not fully mediate between a mother's psychological status and the child's attachment security. These structural relationships were not different between children with pervasive developmental disorders and mental retardation. There were also no significant differences in the structural paths according to children's developmental age.