Pollinosis, a typical seasonal allergy, is a serious public health problem. Limited numbers of patients receive curative immunotherapy instead of symptomatic therapy; however, there are still some concerns about the inconvenience and side effects of subcutaneous injections and sublingual administration caused by immunotherapy. Here, we propose a simple and safe transcutaneous immunotherapy using solid-in-oil (S/O) nanodispersions loaded with vaccine T cell epitope peptides derived from pollen allergen. S/O nanodispersions are oil-based dispersions of antigens coated with hydrophobic surfactants. They have a high potential to deliver biomolecules including peptides or proteins to immune cells in the skin, and to induce an immune response. The result of quantitative and qualitative analysis by in vitro permeation experiments demonstrated the effective permeation of T cell epitope peptides into the skin. Furthermore, in vivo experiments using a pollinosis mouse model indicated that the S/O nanodispersions loaded with T cell epitopes suppressed serum antibody IgE and cytokine production, and alleviated allergic symptoms to a similar therapeutic level to that observed for subcutaneous injection. These results indicate the potential of transcutaneous immunotherapy using S/O nanodispersions for the future treatment of pollinosis.