Ahstract-This paper deals with deflection sensing for robotic control via high speed vision system. Marker is attached to the end effector of the 3-DoF robot arm and the robot is moved to satisfy a line trajectory of the end effector. The motion of the marker attached to the end effector is recorded using the high speed vision system and actual position of the end effector is calculated via image processing of recorded high-frame rate images. We found maximum 1.8 mm position error from the image processing results. We verify that deflection and vibration can be measured by comparing the actual position obtained from image and the ideal position of trajectory planning.