An abnormality detection device includes a processor and a storage unit connected to the processor. The processor is configured to execute an error vector acquisition process of acquiring an error vector representing a difference between a measurement value vector having multiple measurement values measured at a determination time as elements and an average value vector having an average value of the measurement values accumulated in the storage unit as an element, a component acquisition process of acquiring a plurality of components into which the error vector is decomposed with respect to a direction of a singular vector, a comparing process of comparing a value obtained by squaring each of the components into which the error vector is decomposed with respect to the direction of the singular vector with corresponding variance in the direction of the singular vector individually with respect to the direction of the singular vector, and a determination process of performing an abnormality determination on the basis of plural compared results in the comparing process.