Iwate 1st district (岩手[県第]1区 Iwate[-ken dai-]ikku) 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 majority of the prefectural capital Morioka (the whole city without the former village of Tamayama) and Shiwa county. As of 2012, 278,860 eligible voters were registered in the district. Before the electoral reform of 1994, the area had been part of the multi-member Iwate 1st district that elected four Representatives by single non-transferable vote.