The objective of the study is to develop a simple measurement method of the wind-induced response of wind turbine blades under its operation. A 3 dimensional motion analysis software was used. In order to obtain the blade tip vibration data, two hi-speed cameras had to be set so that they conform to the similarity between the measurement and the calibration, and image processing was helpful to have more stable tracing results. An accurate coordinate transformation was also necessary. The obtained response in along-wind direction sometimes had error caused by miss-tracing of the blade tip, and may not be accurate enough. But the obtained response frequency seemed to correspond to the natural frequency of the blades.