1 ) A diagnostic apparatus comprising means for diagnosing a measured object based on time-series data of a plurality of parameters measured from the measured object, the means for diagnosing comprising: a change-point score calculating portion for calculating a time-series change-point score with which each parameter of the plurality of parameters changes according to passage of time based on the time-series data on said each parameter; a change-point correlation calculating portion for calculating a change-point correlation indicating strength by which each of the plurality of parameters is associated with each of other parameters based on the change-point scores of said each parameter and the other parameter; and a parameter outputting portion for outputting a set of parameters of which calculated degrees of associations are higher than a predetermined reference change-point correlation, said set being mutually strongly associated parameters.