Access control appropriate to each processing node is achieved by evaluating information published by the processing node. An access control device (4) ranks subjects of consumption activities by their trust values, and determines whether or not the ranked subjects include any subject whose rank is improved from the last time. When there exists a subject whose rank is improved from the last time, a subject having data to which access control information is set against the subject with an improved rank is made a proposal that the protection level in the access control information against the subject with an improved rank should be decreased. The access control device (4) also judges whether or not the ranked subjects include any subject whose rank is worsened from the last time. When there exists a subject whose rank is worsened from the last time, a subject having data to which access control information is set against the subject with a worsened rank is made a proposal that the protection level in the access control information against the subject with a worsened rank should be increased.