An attribute reading portion (43) reads attribute information (53, 73, 93, 113) stored in a plurality of second units (5, 7, 9, 11). A connection order deciding portion (45) decides optimum order of a plurality of second units in a daisy-chain connection relative to a first unit (3) based on the read attribute information. A selector controlling portion (47) controls selectors (25, 27, 29, 31, 33) based on the decision. Also, according to another embodiment, when card modules (1002, 1003) are connected to a receiver unit main body, a daisy-chain connection of the card modules can be achieved by switches (1042, 1043, 1044, 1045). Then, a synchronizing signal detector circuit (101) detects a packet synchronizing signal in a digital broadcasting signal which is passed through the card modules. A video/sound decoder circuit (1008) decodes the digital broadcasting signal. In case an error is generated in each circuit (101, 1008), a control circuit (1032) disconnects the defective card module from the daisy-chain connection.