A method for producing carbon using less thermal energy is disclosed. Crystalline cellulose and acidic electrolyzed water are introduced into a reaction vessel. The mixture is heated until it reaches a predetermined temperature (230° C. to 250° C.) while being stirred. When the mixture reached the predetermined temperature, this temperature is maintained, and the mixture is kept heated while being stirred for a predetermined period of time (30 minutes). Thereby, carbon is produced in the reaction vessel.