1. A context-awareness system comprising: an event data producer for forming, from node data including a node value relating to an event, event data including an event value converted from the node value; a context producer for forming context information relating to the event from the event data; and an event data manager for storing event data formation suppression information for suppressing a number of formations of event data depending on a number of entries of the event data to said context producer per unit time and event data conversion rules provided for specific event data formation suppression information, wherein said context producer sends the number of entries of the event data per unit time into said event data manager, said event data manager sends, among the stored event data formation suppression information and event data conversion rules, event data formation suppression information and an event data conversion rule corresponding to the number of entries of the event data to said event data producer, and said event data producer forms the event data based on the event data formation suppression information and the event data conversion rule sent from said event data manager and correspond to the number of entries of the event data.