This study was conducted in order to examine the effect of positive meaning of caregiving on caregiving stress of a mother with adult children with developmental disabilities, and the mediating effect of family resilience. To achieve this purpose, the structured survey was conducted with 258 mothers of adult children with developmental disabilities. The results showed that the mean score for caregiving stress of mothers with adult children with developmental disabilities was 2.93 out of 5, which was relatively high. This result shows that positive meaning for the caregiving experience that mothers with adult children with developmental disabilities directly influences caregiving stress. Also, family resilience was found to affect caregiving stress as a mediating effect. To add on, the severity of the disability of the children and the frequency of challenging behaviors were found to affect the caregiving stress as a control variable. On the basis of these results, suggestions have been made on the need for research and support for caregiving stress of mothers with adult children with developmental disabilities, the importance of strength perspectives in a caregiving, and the effects of family resilience as a mediator. This study has meaning as it works as a foundation for related studies, as there is a lack of research on families of adult children with developmental disabilities.