A planar energy conversion device with a plurality of micro-conversion units is provided and includes a carrier. The carrier includes a plurality of cavities arranged horizontally. The cavities correspond in position to the micro-conversion units, respectively. Each micro-conversion unit includes: a magnetic rotor disposed in the corresponding cavity; and at least one ring-shaped stator surrounding the magnetic rotor, the magnetic rotor being integrated into the carrier and including a magnet component and a winding unit. The magnet component has multiple protruding portions horizontally arranged along the edge of the corresponding cavity. The winding unit has multiple winding elements corresponding in position to the protruding portions, respectively.