In this paper, we present our research result that enables users to navigate a very large social network and to take a look at information flows on the network. To this end, we devise two techniques; (i) mapping a very large social network to a 2-dimensional graph layout, and (ii) exploring the graph to all directions with zooming it in/out. With these methods, we can also look through information flows over social networks. Categories and Subject Descriptors H.5.2 [Information Interfaces]: [User Interfaces]; I.3.6 [Methodology and Techniques]: [Interaction Techniques] Keywords Social Network, Information Visualization