1. A semantic information router that determines an event delivery route of an event comprising data and semantic information, being metadata of said data, on a network, based on the information, and is included in an event place that is a place for comparing an event sent from an event sender with a filter in which the semantic information of the event that a plurality of event receivers wish to receive is set as an event acquisition condition, said plurality of said event receivers being different from said event sender, said event place being the smallest unit in which semantic information is described based on a common ontology system to limit an event delivery range, and including, distinct from said event sender, a plurality of semantic information switches that compare the semantic information assigned to said event sent from said event sender with semantic information registered in said filter and delivers said event sent from said event sender to one or more of said event receivers ignited based on the comparison result among said plurality of said event receivers, said semantic information router being serially connected between said semantic information switches and provided with: a path selection function for selecting the event delivery route between the semantic information switches for delivering the event to the event receiver, based on event type, being a template of semantic information, said path selection function incorporating: a function for creating a shared link for forwarding an event, based on physical link information of semantic information switches that deliver an event to an event receiver based on semantic information contained in an event; and a function for routing an event between said semantic information switches based on a shared link established by a shared link object, said function for routing an event being provided with a function for establishing an event path for each event type, by registering a filter for delivering said event to a series of event place objects; and an event sending function for sending said event to said selected event delivery route, said event sending function performing event forwarding between said semantic information switches based on said event route, and said event sending function being provided with: a function for holding the two latest identifiers of event place objects that a forwarded event has passed through as control information; a function for preventing infinite event forwarding by reference to said control information” an event identifier assignment function for assigning each event an identifier that can identify it uniquely; and a detecting function for detecting whether a duplicate event was delivered from a different path, by comparison with event identifiers that were delivered and stored in the past.