The present invention provides a nasal mucosal vaccine composition which is safe, useful as a preventive or therapeutic agent for infectious diseases or cancers, and capable of inducing systemic immune responses and mucosal immune responses effectively. The present invention provides a nasal mucosal vaccine composition to be administered to a human or animal nasal mucous membrane, the nasal mucosal vaccine composition containing at least one antigen excluding antigens derived from influenza viruses; and as an adjuvant, a lipopolysaccharide derived from at least one gram-negative bacterium selected from the group consisting of Serratia, Leclercia, Rahnella, Acidicaldus, Acidiphilium, Acidisphaera, Acidocella, Acidomonas, Asaia, Belnapia, Craurococcus, Gluconacetobacter, Gluconobacter, Kozakia, Leahibacter, Muricoccus, Neoasaia, Oleomonas, Paracraurococcus, Rhodopila, Roseococcus, Rubritepida, Saccharibacter, Stella, Swaminathania, Teichococcus, Zavarzinia, Pseudomonas, Achromobacter, Bacillus, Methanoculleus, Methanosarcina, Clostridium, Micrococcus, Flavobacterium, Pantoea, Acetobacter, Zymomonas, Xanthomonas, and Enterobacter, or a salt thereof.