A communication adapter in one aspect of the present disclosure comprises a plurality of outer surfaces comprising at least two outer surfaces, an interface device, an antenna, and a transmission device. The interface device is provided at at least one outer surface of the at least two outer surfaces and electrically coupled to an electric working machine through the at least one outer surface. The antenna is provided at another at least one outer surface, which is different from the at least one outer surface, among the plurality of outer surfaces, and configured to be capable of transmitting a radio wave for wireless communication with a communication device other than the electric working machine from the another at least one outer surface.
