A conditional access apparatus receives a filter condition from another conditional access apparatus to set the filter condition to a filter unit 1 thereof. When key information meeting the above-mentioned filter condition is outputted from the filter unit 1, the conditional access apparatus informs the key information to the other conditional access apparatus, and also informs the filter condition set to the filter unit 1 by the key information control unit 3 to the other conditional access apparatus and acquires key information meeting the above-mentioned filter condition from the other conditional access apparatus.