As the exoskeleton robot for the assistance of walking is on the rise, HRI (Human-Robot Interaction) come to be an important issue. So in this research the angle following Variable Stiffness Actuator by using cam for overcoming the limitation of volume and weight in existing mechanisms. For this mechanism determinant of stiffness is not an absolute value but it can be change from zero to rigid by the location of the pivot in the gage between the application point of the input force and output force. So it can be miniaturized and have the volumetric advantage by kinematic design. This variable stiffness system make the HRI effective and the safety from injury resulted from the malfunction and the wrong control can be guaranteed.