1. A pathological diagnosis support apparatus which outputs a diagnostic region that is to be used as a target for diagnosis in a specimen image representing a specimen that is a target for pathological diagnosis, the pathological diagnosis support apparatus comprising: a target obtainment unit configured to obtain the specimen image and specimen information related to a scheme for preparing the specimen; a criterion obtainment unit configured to obtain, from a database, a criterion corresponding to the specimen information obtained by the target obtainment unit, the database associating, for each of a plurality of specimens, specimen information related to a scheme for preparing each of the plurality of specimens with a criterion indicating a condition of a positive rate which is to be satisfied by a region that is a target for diagnosis in a specimen image representing each of the plurality of specimens; a determination unit configured to determine, based on the specimen image obtained by the target obtainment unit, whether or not a positive rate calculated for each of regions in the specimen image satisfies a condition indicated by the criterion obtained by the criterion obtainment unit; and an output unit configured to output, as the diagnostic region, each of one or more regions having the positive rate determined by the determination unit to satisfy the condition indicated by the criterion, wherein the criterion associated in the database with the specimen information related to the scheme for preparing each of the plurality of specimens indicates an upper limit of a ratio of a total size of regions selected in descending order of the positive rate calculated for each of the regions in the specimen image representing the plurality of specimens, relative to a size of an entire region of the specimen image, and wherein the determination unit is configured to determine that a positive rate of each of one or more regions having a total size smaller than or equal to the upper limit indicated by the criterion satisfies the condition, the one or more regions being selected in descending order of the positive rate calculated for each of the regions in the specimen image.