A context-awareness system has an event data producer for forming event data from node data including a node value and node information, a context producer, and an event data manager for storing event data formation suppression information and event data conversion rules. The context producer sends the number of entries of event data (the number of inputs) to the event data manager per unit time. The manager sends to the event data producer the event data formation suppression information and event data conversion rules corresponding to the number of inputs. The event data producer forms event data depending on the event data formation suppression information and event data conversion rules corresponding to the number of inputs. Appropriate context information is formed without increasing the amount of resources when data including values related to events are entered in large amount and frequently.