Iwate 1st district is a single-member constituency of the House of Representatives in the Diet of Japan. It is located in central Iwate and consists of the prefectural capital Morioka city and the two remaining towns in Shiwa district. Before 2017, it covered of the majority of the prefectural capital Morioka and Shiwa district. In 2012, 278,860 eligible voters were registered in the district.