To provide an electronic device that can easily update information according to update information sent from a host device.

The host device 1 transmits the update information (firmware or the like) and destination information to an audio unit 2 through a USB(Universal Serial Bus) cable 3. A USB communication microcomputer 21 of the audio unit 2 receives the transmitted update information or the like and discriminates whether or not the information is transmitted to the unit 2 according to the destination information. When the USB communication microcomputer 21 discriminates that the information is addressed to itself, the microcomputer 21 transfers the received update information to a control microcomputer 22 and writes the update information sent from the control microcomputer 22 to a flash memory 24. When the microcomputer 21 discriminates that the update information is not addressed to itself, on the other hand, the microcomputer 21 transmits the received update information to the control microcomputer 22 to allow a flash memory 25 to write it.