Embodiments of the present invention specify a group of sensors detecting normal operation and a group of sensors detecting abnormal operation from time-series data on the sensors without using threshold values that are based on the experience of users. One aspect of an embodiment is a detecting device for detecting changes in the output of a plurality of sensors, in which the detecting device includes: a first output acquiring unit for acquiring a first relevance matrix; a second output acquiring unit for acquiring a second relevance matrix; a change calculating unit for calculating a change matrix representing the degree of change between the first relevance matrix and the second relevance matrix; and a specifying unit for specifying a group of sensors showing a degree of change greater than the others in the change matrix. Other aspects of the present invention include a detecting method and a program.