In the present invention, a first information processing apparatus displays a window for the content on a display device depending on operations to an input device; the first information processing apparatus obtains feedback operation logs including assessment information for the window and date-time information when the assessment information has been input; the first information processing apparatus obtains operation logs including operation information to the input device and date-time information when the operation has been input; the first information processing apparatus obtains communication logs including date-time information when the window has been displayed and information for identifying the window; the first information processing apparatus sends to a second information processing apparatus the feedback operation logs, the operation logs and the communication logs; the second information processing apparatus receives from the first information processing apparatus the feedback operation logs, the operation logs and the communication logs; the second information processing apparatus correlates information included in at least two of the feedback operation logs, the operation logs and the communication logs in chronological order based on the date-time information included in each log; and usability assessment information is thus generated for the content.