A heat generating device 10 has an air-permeable first side 13 located proximal to a wearers body, a second side 14 located distal to a wearers body, and a heat generating member 11 between the two sides. The second side 14 is provided with an adhesive layer 16 for attaching the device 10 to a garment. The first side 13 is formed of a nonwoven fabric 13b having an uneven surface topography. The nonwoven fabric 13b is composed of a first fiber layer 21, inclusive of a first surface of the fabric 13b, and a second fiber layer 22, inclusive of a second surface of the fabric 13b, partly bonded to each other and has a large number of protrusions 24 and recesses 25 on the side of the first fiber layer 21. The first surface is used as the first side 13.
