Objective: The purpose this study is to explore the relationship between grandmothers and mothers when grandmothers take care of their grandchildren, and to understand the particular meaning of it. Methods: The Participants were 5 grandmothers who have supported or have experience in caring for their grandchildren, and their daughters(5 working mothers) who have entrusted their children to them. In-depth interviews were conducted and analysed by the phenomenological qualitative research method. Results: Seventeen sub-constructs and 5 constructs resulted in: (1) Motivation of grandmothers and mothers for taking care of grandchildren. (2) Pressure of grandmothers and satisfaction of mothers for the support. (3) Grandmothers stepping back and saying Not my child and mothers saying It s my child and thinking their influence is big. (4) Consistent sacrifice of grandmothers and mothers who cannot do the same. (5) Grandmothers feeling empty after caring for their grandchildren and mothers realizing their efforts. Conclusion/Implications: This study attempted to understand the relationship between grandmothers and mothers when grandmothers take care of their grandchildren from multi-perspectives. Through the findings, the need for developing healthy relationships and a caring environment for grandmothers and their grandchildren is stressed.