Contents can be opened to a suitable group by a simple operation. A data management method allows a plurality of users to browse stored data. The method includes setting association of first data which is previously set to be opened and at least one second data. Third groups to which these second data is opened are determined based on first groups of the first data set to be opened and second groups to which a user setting the association belongs. Then, the second data are opened to a user who belongs to the third groups.