The present invention provides: a peptide having antibacterial activity; a composition for preventing or treating sepsis comprising same; and an antibacterial composition. More specifically, the peptide according to the present invention has the excellent effects of not only suppressing the growth of bacteria but removing endotoxins derived from bacteria, thus exhibiting an excellent therapeutic effect on sepsis, and thus can be usefully used to prevent or treat sepsis. In addition, the peptide according to the present invention has selectively excellent antibacterial activity against Gram positive/negative bacteria, and thus can be usefully used in an antibacterial composition for Gram-positive/negative bacteria, or to prevent or treat various infectious diseases caused by Gram-positive/negative bacteria. Furthermore, the peptide according to the present invention exhibits excellent resistance against proteolytic enzymes, and is highly stable, and thus is expected to be utilized in various forms, such as a pharmaceutical composition, a cosmetic composition, a food composition, a health food composition, a feed composition, and a quasi-drug composition.