To provide a gel packed sheet which is formed by using a crosslinkable water absorptive polymer and crosslinking this water absorptive polymer with a functional material to make it possible to impart a shape retaining property to a hydrous gel, to prevent loss of a shape, to improve the feel of use and is further formed by incorporating a far IR radiation material into the functional material or laminating and fixing the far IR radiation material on one or both surfaces of a flat bag body, thereby making it possible to effectively impart a thermal effect and cooling effect to the application area of the human body or the deep parts of food and is additionally improved in the feel of use and a warmer and cooler, food warmer, cold pad and food cooler using the same.

This gel packed sheet for imparting a thermal effect or cold effect to the application point is formed by sealing the hydrous gel consisting of water, the crosslinkable water absorptive polymer and the functional material as indispensable components into the flat bag in which the functional material crosslinks the crosslinkable water absorptive polymer to impart the shape retaining property to the hydrous gel.