The purpose of this paper is to understand the digital differentiation in social members’ information use via digital devices. Though the attention to the digital differentiation becomes far more increasing, there are only few literatures dealing with quantitative approaches about the digital differentiation. The term ‘digital differentiation’ represents the availability of the information user. It is different from ‘digital divide’ of which the main parameter is accessibility to the information. Once accessibility meets a certain level, availability is considered as a more important factor than accessibility when evaluating the progress of ICT(Information and Communication Technology). We present a model that can describe the digital differentiation phenomenon by using the methodology borrowed from the graph theory, inverse optimization and other established research theory related to digital differentiation. We provide some insights to reduce digital differentiations and therefore our analysis can be used as a guideline for policy maker who desires to mitigate digital differentiations.