A Study of Emulator with Trema for Ad-hoc Networks Ad-hoc networks can be formed by performing communication between nodes without infrastructure. A lot of Ad-hoc networks are proposed corresponding with each purpose. To evaluate characteristics of the Ad-hoc network, simulation and/or experimentation are used. In the case of using simulation, unexpected situation occurs when the setting condition is not suited for the actual environment. On the other hand with experimentation, we must spend cost of many and lots of time to create real networkenvironments for various situations. In this paper, we wish report about a network emulator in which an Open Flow technology is adopted for examination of Ad-hoc networks. With this emulator, we put several virtual terminals in a Personal computer. Then we create and experiment Ad-hoc networkenvironments with the Ruby scripts. With using this emulator, we experiment for some small Ad-hocnetworks and confirm the characteristics of those networks. With Trema, we can easily define each node and the connections between those nodes. It is possible that we can execute various networkcontrol and transmission command on the created virtual networks.