A scenario analysis control system device includes a start-up reception unit for accepting a periodic start-up, and a scenario storage unit for storing two or more text scenarios, each of which implements a specific function and includes control codes. A priority level definition storage unit stores a priority level and a number of steps executable in response to a single start-up, provided for each of the two or more text scenarios stored in the scenario storage unit. Every time the start-up reception unit accepts a start-up, a scenario analysis processing unit determines which text scenario is to be executed next and which one or more steps of one selected text scenario are to be executed according to the priority levels respectively assigned to the two or more text scenarios. The scenario analysis processing unit then reads a determined number of steps of the selected text scenario from the scenario storage unit and executes them.