The present invention relates to a broken or folded helical peptide, and a use thereof. More particularly, the present invention relates to a Gram-negative bacteria membrane-permeable peptide having a structure in which an alpha-helical double-sided peptide, composed of hydrophobic amino acid and hydrophilic amino acid, is folded or an antimicrobial composition using a Gram-negative bacteria-specific membrane activity thereof an antimicrobial composition for co-administration a conjugate in which a drug is linked to the peptide or an antibiotic comprising the conjugate.