下野国
was a feudal domain under the Tokugawa shogunate of Edo period Japan, located in Shimotsuke Province (modern-day Tochigi Prefecture), Japan. It was centered on Ōtawara Castle in what is now part of the city of Ōtawara, Tochigi. Ōtawara was ruled through all of its history by the Ōtawara clan.