Introduction: Mother as the main attachment figure has undeniable effect on affective development of children. The aim of the current study was to investigate the relationship and predictability of girls’ depression symptoms through mothers’ attachment style.Method: The present study is of descriptive correlational design. The sample included 388 individuals of the second and the fourth grade students of elementary school that had been chosen through multistage random sampling. The Ontario Mental Health and Adults Attachment Style (AAS) questionnaires were used. Data were analyzed using Pearson correlation and multiple regression analysis.Results: The results showed a significant relationship between ambivalent (r=0.41), avoidant (r=0.32) and secure (r=-0.18) mothers’ attachment style and the girls’ depression symptoms. Final results showed that mothers’ ambivalent attachment style had the most power to predict girls’ depression symptoms. Therefore, mothers’ ambivalent attachment style can predict 0.12% of attachment problems in children. Furthermore, avoidant and secure mother’s attachment styles had 0.10% and 0.4% power to predict girls’ depression symptoms.Conclusion: Supporting the attachment theory, the results of this study show the importance of mother-child interaction. Mothers’ insecure attachment style can be a strong predictor of girls’ depression symptoms. Attachment based therapies may be useful to help treat depression in children.