The present invention provides an agent for the prophylaxis or treatment of visceral pain associated with gastrointestinal tract diseases, which contains lysine. Using the prophylactic or therapeutic agent, gastrointestinal tract diseases accompanying visceral pain, such as intestinal disorder, irritable bowel syndrome, functional dyspepsia, gastro esophageal disease, functional abdominal pain syndrome, ulcerative colitis and Crohn's disease and the like can be lo treated or prevented. In addition, pharmaceutical agent, food and drink and dietary supplement for the prophylaxis or treatment of visceral pain associated with such gastrointestinal tract diseases are provided. They are highly effective for visceral pain associated with gastrointestinal tract diseases as compared to existing pharmaceutical agents, show reduced side effects, and are highly effective.