Iida is a city in Nagano Prefecture, Japan. As of 1 March 2019, Iida had an estimated population of 101,536, and a population density of 154 persons per km2. The total area of the city is 658.66 square kilometres. Iida is an environmental model city, a municipality designated by the Japanese government to be a model for making large cuts in greenhouse gas emissions towards a low-carbon society.