The present invention provides a novel peptide based on CAP11 as well as provides an antibacterial agent, an LPS-cell-binding inhibitor, and a drug such as a bacterial-infection-treating agent or an endotoxin-shock suppressant, each containing the peptide as an active ingredient. The peptide has the following amino acid sequence (SEQ ID NO: 1): X01 X02 X03 X03 X04 X02 X03 X03 X05 X04 X03 X04 X02 X01 X03 X02 X05 X03 (wherein X01 represents a cationic amino acid residue or a polar uncharged amino acid residue, X02 represents a non-polar amino acid residue, X03 represents a cationic amino acid residue, X04 represents a non-polar amino acid residue or a cationic amino acid residue, and X05 represents a non-polar amino acid residue or a polar uncharged amino acid residue). Each of the antibacterial agent, lipopolysaccharide-cell-binding inhibitor, and drug (e.g., bacterial-infection-treating agent or endotoxin-shock suppressant) contains the peptide as an active ingredient. The present invention also provides for a peptide comprised of a sequence of cationic and non-polar or polar uncharged amino acids forming an α-helix wherein the amino acids are arranged along the α-helix such that when represented as a helical wheel, there is a substantial bi-lateral symmetry between cationic versus non-polar or polar uncharged amino acids.