To provide a lightweight and simple device to which sharks can hardly approach during surfing.

When a dry cell is positioned close to a shark, it runs away for his life. A surfboard utilizing this nature of sharks has been invented. In the surfboard, a solar power generation part is installed on the body surface part and an exposed electrode is installed on the body rear surface part. When the surf board is used, a weak current flows around it under the sea to generate an electric field. The sharks are hard to approach the surfboard by the electric field produced. The surfboard is invented without changing the shape of the conventional surfboards. Consequently, the users can enjoy the surfing without obstructing the various motions of the surfing.