The relationships between network structures of learners and learning effects in networked learning spaces are not clari.ed yet. In this study, Statistical Physics-like ideas and techniques of the theory of social impact, which have developed in the desciplin of Social Psychology, are applied to investigate these questions. We investigated some effects that network structures provide to learners by a simulation model based on Social Impact Theory. As a result, it is clarified that different charactristics of network structures formed among the learners provide different influences to learning effects. This paper will report these results and discuss.