[2] Per Japanese census data,[3] the population of Iwade has increased rapidly over the past 60 years.

After the Meiji restoration, the area became part of Naga District, Wakayama, and the village of Iwade was established with the creation of the modern municipalities system on April 1, 1889.

However, as the town had a population of more than 50,000 people as of the 2005 census Iwade fulfilled the requirements to gain city status by both the ordinance of Wakayama Prefecture and Local Government Law.

At the request of residents, Iwade decided to gain city status alone, which was attained on April 1, 2006 Iwade has a mayor-council form of government with a directly elected mayor and a unicameral city council of 14 members.

In terms of national politics, the city is part of Wakayama 2nd district of the lower house of the Diet of Japan.