Provide a heating element that can be worn on the body. The heating element is provided with a bag body formed by overlapping two sheets and joining the outer periphery thereof over the entire circumference； the heat generating material enclosed in the bag body； and a cover provided on the second sheet side of the bag body, the cover The sleeve is provided so as to form a space capable of inserting a part of the body with the bag body. At least a part of the second sheet of the bag body is engaged with the cover, and compared with the bonding strength between the sheets of the bag body, The bonding strength of the second sheet of the cover and the bag is small.提供能著裝於身體上的發熱件。發熱件具備有將2枚片材重疊並將其外周緣遍及全周接合而形成的袋體；封入在袋體的發熱材料；以及設置在袋體的第2片材側的蓋套，前述蓋套藉由與袋體之間形成能夠將身體的一部分插入的空間的方式來設置，袋體的第2片材至少有一部分與蓋套接合，與袋體的片材彼此的接合強度相比，蓋套及袋體的第2片材的接合強度較小。
