To reduce transmission paths while maintaining slow driving (low power consumption) when transmitting a signal.

A signal transmitter comprises a parallel/serial conversion part 20 which converts a plurality of first parallel signals A1,..., An outputted synchronously and parallelly to at least a single line of serial signals B1,..., Bn, and the one or more serial transmission paths 22 which transmits the serial signals B1,..., Bn converted by the parallel/serial conversion part 20.