A bus repeater lying within a demodulation IC performs a bus repeat operation after a repeat operation has been made effective, and terminates the repeat operation on an autonomous basis when a stop condition for each serial data is detected. During the repeater operation, control on the direction of data transfer of a master-side IIC bus and control on the direction of data transfer of a tuner-side IIC bus corresponding to a repeat destination are performed by a master-side IIC bus transaction while they are being synchronized with each other. Therefore, the CPU-side IIC bus and the tuner-side IIC bus seem to be through-connected as the flow of the serial data. Further, data transfer can be done only when the swapping of the data with the tuner side is needed.