1. An object collaboration apparatus, wherein objects comprise: a message receiving portion for monitoring and inputting messages that have been sent over a network; a message/action reaction relation storage portion for storing relations between messages and information on actions that are reactions to the messages; and an action execution portion that executes actions in accordance with the message/action reaction relations; wherein if in the message/action reaction relation storage portion, messages associated with an action are expressed as a message pattern and are given as all messages belonging to the scope indicated by that message pattern, and if a message received by the message receiving portion belongs to the scope indicated by the message pattern, then the action is associated with that received message as a reaction.