Immunotherapy is not generally used in Japan and very few medical institutions perform it. For radical treatment, immunotherapy should be selected. However, subcutaneous immunotherapy has not yet gained acceptance. Japanese cedar pollinosis is a seasonal allergic rhinitis that is indigenous to Japan and occurs with a nationwide mean prevalence of 25%. Clinical research on sublingual immunotherapy for Japanese cedar pollinosis has made progress and it should come into practical use within 2–3 years. If sublingual immunotherapy becomes practical, it should provide a new treatment option for Japanese cedar pollinosis.