Disclosed are a flexible electrode substrate including a porous electrode, a method for manufacturing the flexible electrode substrate, and an energy storage element including the flexible electrode substrate. The flexible electrode substrate can be attached to various objects due to the excellent electrochemical properties and the adhesive properties thereof and thus is very useful. In particular, since the flexible electrode substrate can be used as an electrode of an energy storage element, an energy storage element including the flexible electrode substrate can be attached to various objects and thus can be used as a sticker-type energy storage element. In addition, the flexible electrode substrate can be easily manufactured by transfer method using a difference in adhesive strength and thus allows a simple manufacturing process thereof. Furthermore, electrodes having various patterns can be manufactured with high level of efficiency through simple adjustment of the manufacturing process.