An estimation apparatus 1 includes: a correlation index estimation unit 2 configured to receive a variable output by a component 21 as an input, and estimate correlation index information indicating a range that a value of the variable and a correlation can take after a predetermined time, at a normal time; an abnormality degree calculation unit 3 configured to calculate an abnormality degree using the correlation index information; and a causal effect estimation unit 4 configured to estimate a causal effect expressing an index indicating that an abnormality propagates to a variable output by the component 21.