This article discusses a real-time software specification description using a nonprocedural conceptual data model-based language. In the past several years, extensive studies have been carried out on real-time software specification description languages based on the dynamic aspect of real-time systems: timing and state transition, but few are based on the structural aspect. The control information of real-time systems has been more complicated. Therefore, it is also important to describe the structural aspect in a more comprehensible manner. The authors have been studying a nonprocedural conceptual data model-based language, which helps to describe the structural aspect. The language enables automatic program generation and software reusability. This paper describes how to treat the characteristics of real-time software: state transition, timing and external I/O, in the nonprocedural conceptual data model-based language.