The purpose of this study is to introduce socialization resource theory in Korea and to apply it to domestic situation. In this regard, this study focused on the phenomenon of difficulty in relationship adjustment of newcomers, which are the most problematic in domestic organizational socialization. Therefore, the relationship-based socialization resource process model was established to verify the effect of relationship-based socialization resources(organization-provided socialization resource mentoring and individual-provided socialization resource proactivity) on the step-by-step adjustment of newcomers. In addition, if a positive attitude is formed in the organization, it has been verified that they can perform extra-role not required by the organization. Surveys were administered to airport ground staff members of three full service carriers under mentoring for less than two years. Data were analyzed using structural equation modeling. The results show that mentoring provided by the organization and proactivity of the individuals have positive effects in part, or all of the role adjustments at each stage. Next, when a positive attitude was formed in the organization, analysis has shown that they performed an extra role. This study has implication for academics as a cornerstone research that introduces and utilizes socialization resource theory in Korea. Also, it has practical implication because it can be used to solve a problem of initial adjustment in the process of organizational socialization.