Wireless Sensor Network (WSN) consists of embedded devices attaching sensor and microelectronic technology, computational capability, and distributed processing. Due to computing capability, it is interesting to implement in-network processing in WSN. It means that data preprocessing is conducted in network to reduce amount of data and processing time in server. One of in-network processing approach is multiagent-based signal processing. Here, Agents deployed in sensor nodes, including mobile agents, make collaboration for data aggregation and preprocessing. This paper describes our proposed method how multiagent system is implemented in real WSN. The method lists the process how global network information is identified by agents in sensor nodes, mobile agent migration plan is conducted by the intelligent agent in head clusters, and the mobile agent migrates hop by hop and performs collaboration with sensor node agents for data preprocessing. We propose vibration of a concrete beam as the case study. Our simulation and experimental results show that the proposed multiagent system works properly.