The wind response and performance of a tuned mass damper (TMD) are presented based on the system identification and the inverse wind load estimation. The TMD was installed on a 39-story, 184.6m steel building located in Incheon, Korea with a monitoring system consisting of an anemometer, accelerometers, and internet-based data logging system. On Sep. 2, 2010, the building experienced the Kompasu Typhoon, in which the peak wind speed, measured by an anemometer installed on the roof floor, was 49.7 m/s. In order to analyze the behavior of the building during the typhoon, the dynamic properties of building and TMD are identified from the measured responses. The modal wind load is then inversely estimated from the TMD and building accelerations using a Kalman filter, and the vibration reduction performance of the TMD is evaluated.