In this paper, we present a design and implementation of HDML(Handheld Device Markup Language) authoring tool that can create and mange HDML documents easily and conveniently, HDML is a markup language which enable acces to the Web using small mobile equipment through mobile networks. The basic limitation of mobile equipments and technical difficulties such as representation of HDML deck/card, definition of activation in each card and management of Hyper-link between cards are solved, in the development process of the HDML authoring tool.