The present invention provides a novel benzamide derivative represented by formula 1 and an isomer, a pharmaceutically acceptable salt or hydrate thereof, and a composition for activating a 5-HT4 receptor comprising the same, as an active ingredient. Benzamide derivatives of the present invention has superior affinity for 5-HT4 receptors, capability to reduce the gastric evacuation time, capability to alleviate ventricular tachycardia, ventricular fibrillation, torsades de pointes and QT prolongation, and low toxicity. Therefore, benzamide derivatives of the present invention are therapeutically effective for digestive system diseases.