To solve the problem that soap sufficiently containing active seaweed ingredients as soap components has never been seen, since existing methods for extracting, using, or processing seaweed ingredients are problematic although seaweed ingredients are found to be effective for human bodies.

Soap is obtained by mixing viscous extract containing fucoidan that can be obtained from Sargassum horneri, sodium hydroxide (NaOH), and animal or vegetable oil-and-fat that are soap materials, reacting the mixture, and then shaping.