A management server communicable with portable information devices includes: a group generating portion that generates a group to which two or more portable information devices belong; an identification information receiving portion that receives the identification information from a transmission source device, which receives from any one of fixed terminals each located geographically at a fixed position, identification information corresponding to related information assigned to the fixed terminal; a group determining portion that, in response to receipt of the identification information from the transmission source device, determines a group to which the transmission source device belongs; and a linked transmitting portion that transmits the identification information received from the transmission source device, in order to allow each of one or more portable information devices which belong to the group determined, to display the related information corresponding to the identification information received from the transmission source device.