Young children generally learn words from other people. Recent research has shown that children can learn new actions and skills from nonhuman agents. This study examines whether young children could learn words from a robot. Preschool children were shown a video in which either a woman (human condition) or a mechanical robot (robot condition) labeled novel objects. Then the children were asked to select the objects according to the names used in the video. The results revealed that children in the human condition were more likely to select the correct objects than those in the robot condition. Nevertheless, the five-year-old children in the robot condition performed significantly better than chance level, while the four-year olds did not. Thus there is a developmental difference in children's potential to learn words from a robot. The results contribute to our understanding of how children interact with non-human agents.