In this example, by setting the program in this way, a time at which the user sits on the chair is recorded. The user can comprehend the time at which the he or she sits in his or her workplace based on the record and can take a break when a time for which he or she has continued to sit is too long. Alternatively, software outputting an alert from a smartphone based on the detection result of the software 603c may be further embedded. Then, when the user continues to sit for longer than a predetermined time, an alert may be output from the smartphone to urge the user to take a break.