School libraries are required to promote the habit of reading books in elementary school children. It is necessary to cultivate children's interest in books to achieve this goal. In this paper, we propose a user-generated agent (UGA) that introduces books. Elementary school children can program the behavior of the UGA themselves. The UGA not only cultivates the children's interest in the book introduced by the agent, but also their motivation for the presentation by allowing them to design the contents of the agent. We promote the habit of reading by allowing the children to modify the agent's design and giving them the opportunity to refine their ability to promote books.