1. An apparatus for diagnosing a CableCARD-related status of a CableCARD which is inserted into a host device, and performing proper processing according to a diagnosis result in an OpenCable system, the apparatus comprising: a diagnosis unit which diagnoses the CableCARD-related status of the CableCARD, when the CableCARD is inserted into the host device that receives, decodes and outputs a broadcast signal; and a processor which performs processing according to the CableCARD-related status determined by the diagnosis result, wherein the processor performs outputting an error message to a user interface and information indicating to which version software of the CableCARD is upgraded if an error is generated while the software of the CableCARD is upgraded.