The present invention relates to antimicrobial peptides derived from Romo1 protein, and specifically, provides various peptides having the amino acid sequence of the α-helix 2 region of the Romo1 protein and an antibacterial composition containing each of the peptides, as a result of confirming that the peptides have antibacterial activity against gram-positive, gram-negative and multidrug-resistant bacteria. The Romo1-derived peptides and variants thereof have better bactericidal capability against various types of bacteria and multidrug-resistant bacteria than existing antibiotics and antibiotic peptides, and have antibacterial activity against various bacteria in blood vessels, and may be provided as substances for the prevention or treatment of a wide range of bacterial infectious diseases. Thus, a composition containing the antimicrobial peptide of the present invention is expected to be used in various applications, including drugs, quasi-drugs, food and feed additives, pesticide and cosmetic additives, to prevent or treat infectious diseases.