An energy storage device and a method of manufacturing the same are disclosed. The energy storage device includes a circuit board, a conductive cover disposed above the circuit board, a sealing structure, a metal coating layer, and an electrochemical cell. The sealing structure is disposed between the circuit board and the circumference of the conductive cover such that the circuit board, the conductive cover, and the sealing structure together form a sealed space where the electrochemical cell is disposed. The metal coating layer continuously covers a part of the conductive cover, an exposed portion of the sealing structure, and a part of the circuit board. Therefore, even if the energy storage device needs to be heated during a product assembly, the metal coating layer can keep the sealing structure structurally stable, and the electrolyte of the electrochemical cell will not leak; the whole energy storage device therefore can keeps undamaged.