In this study, psychological experiments are conducted to investigate harm-avoidance action characteristics in humans in close contact with robotic devices. For the experiments, a situation is created in which the sharp end-effector tip of a robot suddenly approaches the eyes of a facing participant. The avoidance reaction time is defined as the time interval from the beginning of the end-effector motion to when the participant begins movement to avoid harm. The results suggest that the avoidance reaction time does not depend on the type of work being performed but on the initial distance between the human's eyes and the approaching object. Using this information, safe human-robot working distances can be determined.