An object is to provide an antibody and a vaccine composition which have an ability to practically prevent or treat a Pseudomonas aeruginosa infection, and which can cope with the diversity of clinical isolates derived from patients infected with Pseudomonas aeruginosa. According to the present invention, an antibody against a PA1698 protein that is a type III secretion system component protein of Pseudomonas aeruginosa or against a peptide of the protein, and a vaccine composition comprising the protein or the peptide are provided.