System analysis device, system analysis method and system analysis program

A system analysis device (100) is provided with the following: a whole model generation unit (1021) for generating a whole model that includes a plurality of partial models and that models elements of a system or the entire system; a core model generation unit (1023) that extracts, from a plurality of whole models generated on the basis of the same event, a partial model satisfying criteria for which prediction precision is predetermined, and that generates a core model that integrates the extracted partial model; and a threshold setting unit (1024) that uses a predetermined definition to calculate the distance between the core model and the plurality of whole models, and that outputs the distance as a threshold for an error determination which used the core model.