Provided is a prophylactic and/or therapeutic agent which improves abnormalities of intestinal function in the form of abdominal pain, diarrhoea or constipation, and is useful for preventing or treating functional gastrointestinal disorders. The prophylactic and/or therapeutic agent for functional gastrointestinal disorders contains rifaximin as an active ingredient. Functional gastrointestinal disorders include conditions such as functional oesophageal disorders, functional gastroduodenal disorders (for example, functional dyspepsia), functional intestinal disorders (for example, functional abdominal distension and functional diarrhoea), functional abdominal pain syndrome, gall bladder dysfunction and sphincter of Oddi dysfunction, functional anorectal disorders (for example, functional incontinence, functional anorectal pain and functional defecation disorders), neonatal and paediatric functional disorders (for example, paediatric functional diarrhoea), and functional disorders of infancy and adolescence (for example, paediatric functional abdominal pain and paediatric nonconservative incontinence).
