Active control has been using for buildings in recent years. It has been shown by previous studies that the combination of seismically passive isolation and active control achieves better control performance for earthquakes. However, the control performance of such a system is not guaranteed for a strong wind because the characteristics of seismic waves are quite different from strong winds. This study devised a method of computing mean control force presented a method of designing a control system for along-wind force. This features the design of a building with active control under along-wind force without solving differential equations.