A flavor-improving agent produced by sterilizing a culture which is produced by the cultivation of a microorganism belonging to the genus Pediococcus in a culture medium supplemented with arginine or a product given by a treatment of the culture; a method for improving the flavor of a food by using the flavor-improving agent; a food having an improved flavor; and a method for production of the food. The microorganism belonging to the genus Pediococcus is preferably Pediococcus acidilactici or Pediococcus pentosaseus. The food is bread or the like.
