It is expected that robots play an important role coxisting with human beings in the field of medical application, welfare one and so on.In such a case, the robot should not effect psychological threat to the human.This paper describe the method for the previous announcement in moving of the robotic arm to reduce human _??_ s threat gainst the robot.The notice device is performed by lighting several LED markers attached at the endpoint of the robotic arm.The effectiveness of the proposed method is evaluated as follows.First, the timing against the previous announcement in moving of the robtic arm was investigated by psychological evaluation. As a result, it is found that the timing has an optimal value and it is from 1.0 to 1.5 seconds.Second, the relation between psychological evaluation value and the changing point of velocity was investigated.As a result, it is verified that the psychological threat of the human can be controlled by giving the previous notice of the change of motion of the robotic arm.