An add-on communication apparatus is attached to cable installment type charging control device integrally attached to an electric vehicle charging cable assembly. A wireless communication unit wirelessly communicates with a terminal device. An infrared light receiving diode receives an infrared light having a digital pattern representing an attachment check response signal and receives an infrared light having a digital pattern representing electric vehicle charging related information from the cable installment type charging control device. An attachment check unit checks whether the add-on communication device is attached to the cable installment type charging control device on the basis of the first digital pattern. The attachment check unit changes a state of the add-on communication device on the basis of whether the add-on communication device is attached to the cable installment type charging control device.