A communication device including: a setting portion that sets the communication device as a main device when communication device is connected to another device and receives an electric power from an external power supply, and sets communication device as a client device when communication device is connected to another device and receives an electric power from another device; an update portion that transmits first and second identifiers to another device, receives from another device third and fourth identifiers, forms a network to which communication device and another device belong with second identifier when communication device is set as the main device, and updates second identifier with fourth identifier when communication device is set as the client device; and a wireless communication portion that, when another device is disconnected from communication device, communicates wirelessly with another device with first and third identifiers, and any one of second and fourth identifiers.