children's book
A book written for children, typically including picture books, early readers, and juvenile literature.
I borrowed a picture book from the children's book section of the library.
This author has written many children's books.
童話 refers to fairy tales or children's stories, often traditional or fantastical, while 児童書 is a broader term for any book aimed at children.
Compound of 児童 (child) and 書 (book).