A diagnosis processing device is provided in which diagnosis is realizable by a simple arrangement. A diagnosis processing device (1) of the present invention includes: a learning pattern creating section (10a) for creating a learning pattern by sampling data from a learning image in which abnormality information indicating a substantive feature of abnormality of a target is pre-known; a learning processing section (12) for causing a neural network (17) to learn, by using learning patterns; a diagnostic pattern creating section (10b) for creating a diagnostic pattern by sampling data from a diagnostic image in which abnormality information is unknown; a determination processing section (18) for determining a substantive feature of the abnormality of the target indicated in the abnormality information in the diagnostic image, based on an output value outputted, in response to an input of the diagnostic pattern, from a learned neural network (17) which is a neural network subjected to learning.