Research of the personality trait concepts has shown that children form the Big Five concept that has the same dimensions as that of adults by upper grades in elementary school, whereas it has been suggested that 5- and 6-year-old children have had a single dimension of Goodness (Hayashi, 2004). It was not clear how an undifferentiated concept with a single dimension becomes differentiated by upper grades in elementary school. Thus, this study examined how a positive personality concept becomes differentiated in childhood. Elementary school children (60 second, 67 third, 56 fourth-graders) were presented with action scenes of protagonists who showed positive personality characteristic of each dimension of the Big Five (Extroversion, Attachment, Consciousness, Emotional stability, and Intellect), and told to evaluate the protagonists' personalities. Children's evaluation patterns suggested that only Extroversion was differentiated from other positive dimensions in early-childhood, and that all the five dimensions become differentiated from each other by late-childhood.