Disclosed is a method of manufacturing an anode for a thermally activated reserve battery using a thin metal foam and a cup, which includes rolling a metal foam, coating the metal foam with a molten eutectic salt, impregnating the metal foam with lithium, and providing the metal foam with an electrode cup and a conductive separation membrane, and in which lithium having excellent capacity and output characteristics is employed in an anode for a thermal battery operating at high temperature.