To make a sheet-like heat generator, which is of the type that uses reaction heat emitted in a thermite-like reaction as a heat source, by improving the method of forming an exothermic agent, to expand the scope of the application, and to improve the practicality and convenience.

The sheet-like heat generator 1 is obtained by forming paste 5, containing the exothermic agent comprising a binder 4, and a thermite-like exothermic agent 2 into a sheet-like shape. Its flexural elastic modulus can be improved by kneading fibers 3 in the paste 5 containing the exothermic agent. This heat generator is usable, for example, as a heater element for a road marking material.