The purpose of this study is to understand the different views of grandparent's that are rearing children from the grandmother and working mom as co-caregivers by studying conflicts and the experience made by grandmothers by rearing children through a phenomenological approach, and to help to build healthy relationships and furthermore to promote a healthy educational environment. Data were collected from six working mothers from a child care center in Gyeonggi, and their six grandmothers who were rearing grandchildren through in-depth interviews, emails and observation based on the instruction of semi-structured interviews. For analysis, a phenomenological analysis method is used. As a result, 78 meaning units, 15 sub-elements and 6 theme categories were drawn. Theme categories were (1) grandmothers' rearing experience; perform a double-role through grandchildren-rearing (2) working moms' rearing experience; conflicts over ideologue of motherhood (3) grandmothers' rearing positive effect: increasing grandmothers' efficacy and intimate relationships with grandchildren (4) working moms' rearing positive effect: reducing working moms' children-rearing stress (5) negative effect: increasing grandmothers' children-rearing stress and working moms' low children-rearing efficacy (6) rearing conflicts: the two mothers' conflicts over children-rearing values. Through the study, it implies that social intervention is needed to solve the conflicts between two mothers over the rearing attitudes and methods as understanding and intervention is needed.