It is commonly agreed that architecture design is essential for development of complicated software and that depending on viewpoints software architecture can be captured in various views. Among them, the logical view is the earliest and foremost view that software developers should consider because it shapes the later phase of architecture design and the subsequent development. In this paper, we present an architecture description language for logical architecture and its associated design method. The main characteristic of the language and the design method are that they support recursive top-down design so that logical architectures for software systems of any scale and complexity can be designed. We apply them to a realistic system and show their efficacy.