An object of the invention is to provide a structure for preventing easy pullout of a plug that has been inserted into the socket of a device main body, to make the user aware that plug pullout prevention is important, and to fully exhibit the functions of the device. The present invention detects the temperature of a thermal unit and the temperature of a holding unit and corrects the temperature of the thermal unit based on the temperature of the holding unit so that effects from the temperature of a surrounding area can be corrected and the temperature can accurately be detected without scarring a surface of the rotating body. In other words, the inventive porous material can be used to separate a mixture of gases based upon the different working diameter of each of the gases. Also provided is a second member to which the first member is mated.