This paper focuses on maintaining a bridge's safety by developing a daily management system. And the purpose of this study is the development of the health monitoring system. It supports the maintenance by using sensor network and Independent Component Analysis (ICA) when there are some troubles in a bridge. The result of this study brings out the vibration behavior of the overall structure in a bridge. This vibration is caused by the external force such as wind pressure, and running vehicle. The character frequency was extracted from the analysis result using ICA and Spectral Analysis. Even if the vibration behavior caused by external force is very small in the bridge, ICA can detect the vibration response from the bridge. The actual sensor network system has been developed and the performance is demonstrated.