To provide a system which certifies that contents were formally published in a homepage for a certain period.

This system is equipped with a monitoring object storage means which stores address data regarding a monitoring object computer and publication period data regarding the publication period of the contents, a monitoring time determining means which determines the monitoring timing of the publication period data, a contents gathering means which gathers contents published on the monitoring object computer in the 1st monitoring timing determined by the monitoring time determining means, a contents storage means which stores the contents gathered by the contents gathering means together with the gathering time data, and a comparing means which compares the latest contents gathered by the contents gathering means for the 2nd and succeeding times with the contents stored in the contents storage means together with the last gathering time data to check whether there are differences; when the comparing means judges that there is no difference, the comparison result and the gathering time data are stored in the contents storage means.