Abstract: The present invention relates to novel antibiotic peptides which possess antibacterial and/or antifungal activities causing no cytotoxicity, and to antibacterial and/or antifungal agents containing said peptides as active ingredients. In accordance with the present invention, it has been discovered that a number of chemically-synthesized peptides which are derived from Tenecin, show superior antibacterial and/or antifungal activities, while causing no untoward effects, and they can be applied for the development of antibacterial and/or antifungal agents.