Provided are: a Clostridium difficile growth inhibitor which comprises, as the active ingredient, a propionic acid bacterium and/or a fermentation product thereof； and a prebiotics composition which has an effect of inhibiting the growth of Clostridium difficile. Also provided are: a Clostridium difficile growth inhibitor which comprises, as the active ingredient, 1,4-dihydroxy-2-naphthoic acid (DHNA) and/or an organic acid； a prebiotics composition which has an effect of inhibiting the growth of Clostridium difficile； and a food composition comprising the same. Also provided is a method for inhibiting the growth of Clostridium difficile, said method comprising taking or administering the aforesaid substances.
