A communication-adapter mounting device is used for mounting a communication adapter that relays communication between an air-conditioning apparatus and another apparatus. The communication-adapter mounting device includes a body into which the communication adapter is to be accommodated and from which the communication adapter is allowed to be removed, and a clip to mount the body to a housing of the air-conditioning apparatus. A mounting plate of the body includes a mounting hole for securing the communication-adapter mounting device to an installation location in which to install the communication adapter. Further, the body has a clip holding mechanism to hold the clip and to allow the clip to be removed.