The present invention relates to a synthetic clay composition which does not harden and thus can be repeatedly shaped without water while maintaining the shape for a long time and, particularly, to a novel synthetic clay composition and a method for preparing the same. The synthetic clay composition is soluble in water, and thus can be easily washed and is highly safe for the human body. Further, the synthetic clay composition is light and can be repeatedly newly shaped as desired. In addition, the synthetic clay composition has an excellent ability to maintain a shape, and thus can maintain the same shape in an agglomerated form for a long time, and can be used for play such as throwing.