A serial data transfer apparatus includes a transport controller that performs a process of a transport layer, a link controller that performs a process of a link layer, and a physical layer circuit that performs a process of a physical layer. The serial data transfer apparatus transmits and receives data with a destination apparatus via a serial bus. The link controller outputs idle data, which is received from the destination apparatus, to the physical layer circuit, and stops to operate of a unit responsible for generating data to transmit to the destination apparatus while outputting the idle data to the physical layer circuit. This enables to output idle data defined in the standard in an idle period of the serial data transfer apparatus and also reduce the power consumption.