The present invention relates to a pharmaceutically acceptable salt of alkylcarbamoyl naphthalenyloxy octenoylhydroxyamide or of a derivative thereof and a method for preparing same, and can improve moisture stability while maintaining the characteristics, such as the efficacy and effective dose, of a pharmaceutically acceptable salt of alkylcarbamoyl naphthalenyloxy octenoylhydroxyamide or of a derivative thereof. In addition, the present invention can simplify the production and manufacturing process of a formulation by improving hygroscopicity.