An insulating material is used that contains a silica xerogel, and a nonwoven fabric fiber capable of generating carbon dioxide by reacting with atmospheric oxygen at a temperature of 300° C. or more. The insulating material uses oxidized acrylic as the nonwoven fabric fiber. A device uses the insulating material installed as a part of a heat insulating or a cold insulating structure, or installed between a heat-generating part and a casing.