Invoked Reality (IR) research uses a variety of sensors and projection equipment for Natural User Interface (NUI) interaction. Such equipment requires an appropriate action region, which needs to be considered when implementing an IR environment. Accordingly, the implementation of an IR environment is problematic because of the arrangement of this equipment. The research presented in this paper overcomes this difficulty by proposing the "IR Simulator." This simulator facilitates the design of and experimentation within the IR environment in a virtual environment. IR Simulator comprises an "experimental space editor" and "simulation manager." IR Simulator enables design in diverse kinds of IR environments using its GUI-based experimental space editor. It also provides interaction with external IR libraries through the external IR library-interworking interface. Moreover, it enables simulation on the library connected on the basis of the virtual sensor data generated by the implementation of the proposed simulator. In accordance with experiments using the proposed simulator, a variety of IR environments could be generated and an arm motion recognition library could be simulated. Furthermore, the same environment generated by the simulator was easily implemented in the actual environment on the basis of the design results from the simulator. The experiment on the arm motion recognition library used in the simulator in the real environment was similar to the results obtained by the simulation.