The present invention provides a device for mounting a wireless device case. A first mounting ring (340) and a second mounting ring (360) are fixed to a wireless device case (200) using fastening screws (347, 367). The first mounting ring (340) and the second mounting ring (360) are fitted to a measurement display section (104) from above thereof, and a common mounting bolt (301) is passed through the rings (340, 360) to fasten the rings together. The configuration allows a wireless device to be independent of a meter and to be easily mounted to the meter.