Electronic Commerce technologies have been studied widely in the field of Economics and Informatics. In recent years, there are multiple aspects of researches in electronic commerce including supply chain model, Internet auctions, Internet volume discounts, electronic bank and sk trading, and several others. The increase of Electronic Commerce research activities can be observed in a variety of the fields. The aim of this book is to encourage activities in this field, and to bring researchers with an interest in Electronic Commerce. This book is edited from some aspects of e-commerce researches including theoretical mechanism design of trading based on auctions, allocation mechanism based on negotiation among multi-agent, case-study and analysis of e-trading, data engineering issues in e-commerce, and so on. The reason why the many aspects are included is to show the outline of the newest research result of e-commerce research.