Endo-(8-methyl-8-azabicyclo[3.2.1]oct-3-yl) 1-isopropyl-2(1H)-quinolone-3-carboxylate represented by Formula (I):
or an acid addition salt thereof acts on a serotonin 4 receptor thereby to have a serotonin-like receptor stimulating activity, therefore has an action on activating gastrointestinal motor functions and thus is effective for the improvement of gastrointestinal conditions such as heartburn, anorexia, bowel pain or abdominal distension accompanied by chronic gastritis or postoperative gastroparesis, and further for the treatment of gastro-esophagal reflux, intestinal pseudo-obstruction or constipation.