Heat storing material, composition thereof and their use

A heat-accumulative material composed of a polymer or oligomer having a melting point of −10 to 100° C. and latent heat of 30 J/g or more for use around a body, and heat-accumulative composition comprising the same heat-accumulative material. The heat-accumulative material tends to be kept at a constant temperature more effectively by absorbing heat as ambient temperature increases to melt, and releasing heat as ambient temperature decreases to solidify, to moderate the effect of changed ambient temperature, and thereby to exhibit the function as a heat-accumulative material. They have a sufficiently high viscosity, preventing the heat-accumulative material from flowing out even when it is molten. Each of the heat-accumulative material and composition can be made into a heat-accumulative film or sheet, laminate, molded article, composite fiber and cloth which can be suitably used around a body.