A policy system that can add/delete policies easily to/from devices as needed through existing interfaces and enable policies to be developed quickly on-site and applied to devices provided with new device interfaces and new commands. A policy manager registers each defined policy type in a database after the definition and searches and refers to the defined policy type upon receiving a policy so as to check the validity of the policy. A policy agent registers each defined policy translation rule in a database after the definition. Upon receiving a policy, the policy agent searches and uses the translation rule to translate the policy to a command string.