1. An availability evaluation device comprising: a state transition storage unit configured to store definitions of a plurality of state transitions corresponding to configurations of a system; an additional state transition storage unit configured to store definitions of state transitions that are used when operating the system and that are different from the plurality of state transitions; an operation registration unit configured to receive the definitions of the state transitions used when operating the system and register the definitions in the additional state transition storage unit; an availability analyzing unit configured to analyze the availability of the system based on the definitions of the state transitions stored in the state transition storage unit and the definitions of the state transitions stored in the additional state transition storage unit; an operation analysis unit configured to analyze common state transition patterns in at least part of the definitions of the plurality of state transitions used when operating the system and stored in the additional state transition storage unit; and an operation analysis result output unit configured to output analysis results obtained by the operation analysis unit.