To obtain a solution that satisfies the restrictions for the agents as a whole by making every agent improve in steps the current assignment method in cooperation with each other to detect such assignment of resources that can satisfy the restrictions of resources and then to execute the jobs of all agents.

Every agent reports the value of the job that is temporarily set to other agents (S11, S13), calculates the largest improvement degree of the evaluation value that is obtained by changing the assignment of its own plan based on the assignment of plans of other present agents after the 'ok?' messages are received from all other agents, and sends the improvement decrees to other agent in the improvement messages to set an improvement message wait mode (S17 to S21). If its own improvement degree of every agent is larger than those of other agents, the former degree is changed (S25, S27) after the improvement messages are received from all other agents (S23).