A communication adapter capable of performing communication even in a case where power supply from an external device has ceased is provided. The communication adapter includes a power storage configured to receive power supplied from an external device and store the power, a communication unit configured to receive power supplied from the power storage, a control unit configured to communicate with an external management device via the communication unit, a first power supply line through which the power supplied from the external device goes to the control unit, thereby bypassing the power storage, and a second power supply line through which the power supplied from the power storage goes to the control unit.