A wireless temperature sensor that has an ease of manufacture and an improved reliability is provided. The wireless temperature sensor includes a first structure having an antenna having an antenna electrode and a GND electrode disposed in an insulating substrate, a temperature detection device fixed on an opposite surface of the first structure to a surface in which the antenna electrode is disposed, and a second structure disposed on the side of a side wall of the temperature detection device and joined to the first structure. The temperature detection device is fixed on the first structure so as to be electrically connected to the antenna electrode and the GND electrode.