Continuous structural health monitoring of a steel building specimen on the full-scale shaking table test is conducted to investigate modal properties of a passively controlled steel building subjected to large earthquakes. Changes in the dynamic properties are evaluated from the continuous ambient vibration test, which are related to damage detectability from ambient vibration or earthquake observation on real buildings. The results in the paper are summarized as follows: (1) The shifts in the first natural frequency due to the construction works and seismic experiences can be detected clearly. (2) Within tiny deformation of ambient vibration different characteristics in natural frequency or damping factors is observed in use of different types of seismic control devices.