The present invention aims at providing a vaccine composition capable of being administered to an intraoral mucous membrane, ocular mucous membrane, ear mucous membrane, genital mucous membrane, pharyngeal mucous membrane, respiratory tract mucous membrane, bronchial mucous membrane, pulmonary mucous membrane, gastric mucous membrane, enteric mucous membrane, or rectal mucous membrane, that is safe, useful as a prophylactic or therapeutic agent for infectious diseases or cancers, and capable of effectively inducing the systemic immune response and mucosal immune response. The present invention provides a mucosal vaccine composition to be administered to at least one mucous membrane selected from the group consisting of a human or animal intraoral mucous membrane, ocular mucous membrane, ear mucous membrane, genital mucous membrane, pharyngeal mucous membrane, respiratory tract mucous membrane, bronchial mucous membrane, pulmonary mucous membrane, gastric mucous membrane, enteric mucous membrane, and rectal mucous membrane, the mucosal vaccine composition containing: at least one antigen; 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, wherein a mass ratio between the adjuvant and the antigen (total mass of the adjuvant/total mass of the antigen) is 0.002 to 500.