Nowadays, media has more influence on the society. But, the ethics of media producers are decreased due to lack of consideration on whether the contents are suitable for children or not. Consequently, the children may imitate inappropriate behaviors without knowing. Recently, game-based mobile learning application has been applied as a learning media for children because it is more fascinating and effective than traditional learning. From our literature survey, the learning media about Thai social etiquette is still a few and not attractive for children. However, it is still important to cultivate the children's good manners. The objective of this research project is to develop a game-based mobile learning application called “Kiddy Manner”, which is an android application for children learning Thai social etiquette. The target users of the application are children ages 6-9 years old (grades 1-3) in elementary schools. The ultimate goal of this research project is to encourage the children growing up to be the well-behaved persons in the society.