The present invention is to provide a computer system, a method, and a program for diagnosing a subject that improve the accuracy of diagnosis by combining a plurality of time-series image data more than that by a conventional single image analysis. The computer system for diagnosing a subject acquires a plurality of first subject images with time series variation of the subject, analyzes the acquired first subject images, acquires a plurality of second subject images with time series variation of another subject in the past, analyzes the acquired second subject images, checks the analysis result of the first subject images and the analysis result of the second subject images, and diagnoses the subject based on the check result.