In order to configure a microneedle to be more suitable for administering a vaccine antigen, the present invention is a formulation having a dissolving-type microspike which is used as a microneedle in which a vaccine antigen is stabilized, and which includes a vaccine antigen, an ionic polymer base material, and at least one species selected from the group consisting of a non-reducing sugar, a sugar alcohol, cyclodextrin, and a surfactant.