A transmission/reception system 1 includes a transmission device 10 configured to transmit image data and a reception device 20 configured to receive the image data transmitted from the transmission device 10. The transmission device 10 includes a serializer 11, an encoding unit 12, a data buffering unit 13, a data selection unit 14, a counter 15, and a synchronization signal generation unit 16. The data buffering unit 13 buffers data every n bits in synchronization with the clock. The data selection unit 14 outputs m-bit data selected from the data buffered by the data buffering unit 13 on the basis of a count value from the counter 15.