Recently, many system development projects have been using a screen prototype. On requirements definition phase, screen prototyping is effective to decrease some troubles, which are misunderstanding, lack of requirements, and conflict among requirements and so on. On the other hand, there are some problems caused by using a screen prototype. A screen prototype has been mainly used to review system's user interface requirements. Therefore, it could be difficult to review other type of requirements (i.e. requirement about interaction-process between system and user and decision rule which system executes). This paper proposes a system prototype generation tool which transforms three requirements artifacts into system prototype. Three requirements artifacts are business process, business rule and user interface. We also adapt this tool to the requirements definition phase of system development project. As a result of the case study, we introduce that the proposed tool is helpful to review requirements precisely and detect requirements errors.