The main purpose of the study was to examine the mediating effects of parent attachment and peer attachment on the relationship between negative life events and problem behavior among adolescents in institutional care. The subjects were 472 adolescents in 75 group homes and in 12 care institutions in Jeonbuk, Jeonnam province and G metropolitan city. The data were analyzed using SPSSWIN 27.0 program and SPSS Process macro program. In order to verify the significance of the mediation effect, bootstrapping was conducted. The results were as follows: First, life events of adolescents in institutional care were not significantly correlated to both internalizing and externalizing problems whereas violent events of adolescents in institutional care were positively correlated to both internalizing and externalizing problems. Moreover parents attachment, and peer attachment of adolescents in institutional care were negatively correlated to both internalizing and externalizing problems. Second, parent attachment and peer attachment of adolescents in institutional care had partial mediating effects between violent events and internalizing problems. However parent attachment of adolescents in institutional care had full mediating effects between violent events and externalizing problems whereas peer attachment had partial mediating effects.