The purpose of this study is to describe the young children's learning of a living thing and the role of their teacher at a breeding activity. We focused on 6-year-olds at kindergarten, participated in the breeding of beetles. In our observation, children interacted with beetles, having intellectual curiosity, and gained new biological knowledge about them. In addition, they seemed to regard the beetles as creatures which had minds like human beings, but it was hard for them to be sympathetic to the beetles at all times. A teacher gave the children some clues for their intellectual findings, and admonished them to care the beetles more gently. These findings indicate that the teacher played a role to keep the balance of children's learning between natural science and bioethics at breeding.