April 2nd is the birthday of Danish fairy tale master Andersen. 1967, ibby designated this day as "International Children's Book Day" to arouse people's love for reading and pay attention to children's books.

At present, ibby has 70 national chapters. Every year, a national chapter is selected to hold the International Children's Book Day, and the theme of the activity is determined by it. Many national chapters also promote "International Children's Book Day" by organizing activities such as media, schools and public libraries, and organize various activities, such as meeting writers and illustrators, writing competitions or announcing book prizes.