An objective of the disclosed invention is to derive a more apt similarity by taking into account all components up to and including lower order components that are included in a model. The disclosed invention also allows carrying out more efficient information system building.An information processing device (1000) includes a model storage unit (10), a component correspondence determination unit (20), and a similarity computation unit (30). The model storage unit (10) there among stores a system model that includes at least one component. The component correspondence determination unit (20) determines a correspondence relationship between components included in two system models (A, B) that are read out from the model storage unit (10), on the basis of commonality of lower order components included in the components. The similarity computation unit (30) calculates the similarity of the two system models on the basis of the correspondence relationship between the components that is determined with the component correspondence determination unit (20).