The present invention relates to a method for preparing N-[[1-{3-(1,2,3-triazol-1-yl)propyl}piperidin-4-yl]methyl]-4-amino-5-chloro-2-methoxybenzamide, which is a novel benzamide derivative as a 5-HT4 receptor agonist, or a pharmaceutically acceptable salt thereof; to a novel intermediate capable of being used in the preparation of the compounds; and to a method for preparing the same. The preparation methods of the present invention can be useful for mass production since a low-priced reagent and intermediate are used and the number of reaction processes is decreased, thereby saving preparation costs and improving the yield.