The method for manufacturing a supercapacitor according to the present invention includes the following steps. First, stack a bottom electrode plate and a top electrode plate in parallel. Then, install a first rubber frame and a second rubber frame face-to-face on the bottom and the top electrode plates. The first rubber frame is adapted with a first opening, while the second rubber frame is adapted with a second opening. Next, install an isolation membrane in a space surrounded by the first and the second rubber frames. Afterwards, bind the first and the second rubber frames. Then, produce vacuum in the space. Next, place the bottom and the top electrode plates into an electrolyte to make the electrolyte flow into the space. Finally, use a first resin to seal the first and the second openings. Thereby, the short-circuit phenomenon caused by long-term usage of the supercapacitor can be prevented. In addition, the structural strength of the supercapacitor can be reinforced to avoid electrolyte-leakage phenomenon.