Provided are an agent for improving bacterial flora in the oral cavity, said agent selectively inhibiting the growth of periodontal disease-causing bacteria in the oral cavity and selectively promoting the growth of non-pathogenic bacteria to thereby improve the balance of the bacterial flora, and an oral composition comprising the agent. An agent for improving bacterial flora in the oral cavity which comprises (A) one or more members selected from among spermine, spermidine, sialic acid and lactoferrin, and (B) one or more members selected from among lactulose, an oligosaccharide and a sialic acid-containing disaccharide, and an oral composition which comprises the agent as an active ingredient. An oral composition which comprises one or more members selected from among spermine, spermidine and sialic acid as component (A) and the aforesaid component (B)； an oral composition which comprises lactoferrin as component (A) and (B-3) a sialic acid-containing disaccharide as component (B)； and an oral composition which comprises lactoferrin as component (A) and (B-1) one or more members selected from among lactulose and an oligosaccharide as component (B).L'invention concerne un agent pour améliorer la flore bactérienne dans la cavité buccale, ledit agent inhibant sélectivement la croissance de bactéries provoquant la maladie parodontale dans la cavité buccale et favorisant sélectivement la croissance de bactéries non pathogènes, ce qui lui permet d'améliorer l'équilibre de la flore bactérienne, ainsi qu'une composition buccale comprenant l'agent. L'invention concerne un agent pour améliorer la flore bactérienne dans la cavité buccale qui comprend (A) un ou plusieurs éléments sélectionnés parmi la spermine, la spermidine, l'acide sialique et la lactoferrine, et (B) un ou plusieurs éléments sélectionnés parmi le lactulose, un oligosaccharide et un disaccharide contenant de l'acide sialique, ainsi qu'une composition buccale qui comprend cet agent en tant que principe actif
