File-sharing Peer-to-Peer systems are effective for autonomous information retrieval over the networks. However, the previous information retrieval schemes such as Gnutella and Local Indices have bad performance and large overhead. In order to solve these drawbacks, this paper proposes a dynamic information retrieval scheme, in which indices are dynamically allocated in appropriate nodes adaptively to variation of traffic patterns caused by query messages. The simulation experimental results show that the proposed scheme has good performance with reasonable overhead even when the traffic patterns vary as time proceeds.