1. A group environment setting method in a network system consisting of plural computers where plural participants constitute a group and perform a cooperative operation, comprising the steps of: registering environment setting information for setting an application environment for the cooperative operation according to a group; reading, when a group is designated by a participant, environment setting information corresponding to the designated group from said registered environment setting information; applying the read environment setting information as environment setting information of said participant who designated the group; and notifying other participants of the read environment setting information so that an equivalent application environment is set for all participants of the designated group before each participant performs the cooperative operation.