In this paper, a dynamic MAS reallocation method is proposed for the WiMedia MAC. WiMedia MAC configures a fully distributed network. WiMedia devices communicate during Superframe which is a communication unit in WiMedia MAC. guarantee QoS, WiMedia MAC uses a TDMA based time slot reservation protocol named distributed reservation protocol (DRP). On existing WiMedia networks, if any conflict occurs in the process of DRP reservation, the transmission in the present superframe will be given up and the transmission will be done in the next superframe. When a delay is expected due to a DRP reservation conflict, the dynamic MAS reallocation can search for other MAS in real time to avoid the conflict. By applying the Dynamic MAS reallocation method, the delay (65ms) for the length of a superframe can be prevented and QoS can be guaranteed more effectively. However, due to only a 12 μs timing allowance between beacon period and data period, the process of our proposed method cannot be completed in time if the entire process is handled by software. Therefore, we designed a hardware module for the proposed method and merged it into WiMedia UWB MAC-PHY system.