1. An information sharing processing method comprising the steps of: a page display processing step for acquiring a file from a predetermined server on a network and displaying said file as a page, wherein said file is described in a predetermined page description language and includes a description of link information to another file on said network; a common-screen display processing step for displaying an icon representing a user at a position on a common screen shared with said user and displaying a message issued by said user making an access to the same page as said page displayed at said page display processing step in which information on said position is specified by said user in shared data transmitted by said user by way of a shared server on said network; and a screen superposition processing step for superposing said common screen displayed at said common-screen display processing step on said page displayed at said page display processing step.