This study focused on the stability and reciprocal effects between adolescent attachment trauma, smart phone addiction, and depression. Using autoregressive cross-lagged modeling, data from the 2nd to the 6th wave of the Korean Children and Youth Panel Study (KCYPS) were analyzed. The sample consisted of 2,280 adolescents who were 8th graders in 2011. Data were collected at four different phases: when participants were in 8th grade, 9th grade, 10th grade and 12th grade. First, the effects of adolescent attachment trauma, smart phone addiction, and depression showed stability from the 8th grade to the 12th grade. Second, adolescent attachment trauma at T2(8th grade), T3(9th grade) and T4(10th grade) had effects on depression at T3(9th grade), T4(10th grade) and T6(12th grade), respectively, but not on smart phone addiction. Depression at T2(8th grade), T3(9th grade) and T4(10th grade) had effects on smart phone addiction at T3(9th grade), T4(10th grade) and T6(12th grade), respectively, but not on adolescent attachment trauma. In terms of parent effects, adolescent attachment trauma influenced depression only. Finally, smart phone addiction and depression had reciprocal effects. The present study found the stability of adolescent attachment trauma, smart phone addiction, and depression. Furthermore, this study identified the parent effects between adolescent attachment trauma and depression, and reciprocal effects between smart phone addiction and depression.