This paper presents characteristics of motion-induced wind forces acting on a rectangular high-rise building with a side ratio of 2 during across-wind and torsional vibration. The motion-induced wind forces are measured by a forced-vibration method in a wind tunnel. Results are as follows; (1) The characteristics of motion-induced modal wind force acting on a high-rise building with a side ratio of 2 during turbulent flows are different from those during a uniform smooth flow for reduced wind speed of 7 or more. (2) The wind speed in which the out-of-phase component of motion-induced wind forces show a positive value during turbulent flows is limited to the vicinity of 5 for the reduced wind speed for across-wind vibrations. In the case of the motion-induced torsional moment. the positive value of out-of-phase components is shown in the wind speed area where the reduced wind speed is 5 or more. (3) The aerodynamic dampings obtained from the out-of-phase components of motion-induced modal wind force are in agreement with those from elastic model test. And the wind responses of a building obtained from wind response analysis using the aerodymanic dampings are in agreement with those obtained from the elastic model test. (C) 2001 Published by Elsevier Science Ltd.