Abstract: An abnormality detection apparatus acquires observation values serving as indexes of an operating state of a monitoring target apparatus at predetermined timings in a process executed repeatedly in the monitoring target apparatus. The abnormality detection apparatus applies statistical modeling to a summary value acquired by summarizing the observation values, to estimate a state in which noise is removed from the summary value, and generate a predictive value acquired by predicting a summary value of a next period based on the estimating. The abnormality detection apparatus detects presence/absence of abnormality of the monitoring target apparatus based on the predictive value.