To provide a novel and safe antibacterial peptide-inducing agent with no side effect, said antibacterial peptide-inducing agent exerting the biological self-defense mechanism that human possesses. [Solution] Provided is a novel antibacterial peptide-inducing agent that comprises a lactic acid bacterium as an active ingredient. As the lactic acid bacterium, viable cells may be taken as such. Alternatively, the lactic acid bacterium may be taken in the form of a so-called viable lactic acid bacterial cell-containing material produced via fermentation with the lactic acid bacterium. When the in vivo antibacterial peptide-inducing agent according to the present invention is taken, the antibacterial peptide is induced in vivo. As a result, various effects of, for example, improving the immunity due to prophylaxis of various infectious diseases, anti-aging and extending healthy life, can be expected.