The technology of artificial intelligence is increasing its importance thanks to the rapid growth of the Internet and computer technology. In Japan, the annual conference series of JSAI (The Japanese Society for Artificial Intelligence) has been playing a leading role in promoting AI research, and selected papers of the annual conferences have been published in the LNAI series since 2003. This book consists of award papers from the 21st annual conference of JSAI (JSAI 2007) and selected papers from the four co-located workshops. Seven papers were awarded among more than 335 presentations in the conference and 24 papers were selected from a total of 48 presentations in the co-located workshops: Logic and Engineering of Natural Language Semantics 2007 (LENLS 2007), the International Workshop on Risk Informatics (RI 2007), the 5th Wo- shop on Learning with Logics and Logics for Learning (LLLL 2007), and the 1st International Workshop on Juris-informatics (JURISIN 2007). The award papers from JSAI 2007 underwent a rigorous selection process. Firstly, recommendations were made from three people (Session Chair, session commentator and one PC member) in each session, and then recommended - pers were carefully reviewed and voted for by PC members for final selection.