A capacitor and a manufacturing method thereof are provided. The capacitor includes a porous substrate, an electrolyte composition, and a pair of electrodes. The porous substrate has a plurality of holes. The electrolyte composition is located in the holes of the porous substrate, and the electrolyte composition includes an electrolyte solution and a nano carbon material dispersed in the electrolyte solution. The electrodes are respectively located on two opposite surfaces of the porous substrate.