The purpose of this study is to examine whether the ego–identity plays a mediating role on the relationship between depression level and cyber relationship addiction by college students. For this study, a total of 599 college students which made up of 326 male and 273 female were randomly sampled, and the collected data were analyzed by Pearson correlation analysis, regression analysis, mediation regression analysis of Baron and Kenny using SPSS 22.0. The main analysis results were as follows: First, the higher the depression, the higher the cyber–relationship addiction. The more affirmative the ego–identity, the lower the cyber–relationship addiction. Secondly, ego–identity had a partial mediating effect on the relationship between depression and cyber–relationship addiction for male college students. However, it does not show any partial mediating effect for female college students. this study can be used as a basic data for establishing countermeasures for cyber–relationship addiction problem that is raising to be a social problem.