Abstract: The present invention relates to a method for preparing monoglyceride sulfonate that is useful for a cleansing agent for a human body, economically in a large amount, from an inexpensive fatty acid using a convenient manufacturing unit. The present invention also provides a soft soap composition comprising monoglyceride sulfonate and a fatty acid soap, which has superior molding and stamping workability, softness, smoothness, foamability, and moisturizing ability. The present invention also provides a method for preparing a salt-containing soft soap using the fatty acid used for preparation of the monoglyceride sulfonate, which contains a lot of salt, so that is softens skin, easily removes waste materials, prevents irritation, promotes blood circulation, and prevents depilation and dandruff.