Izu is a city located in central Izu Peninsula in Shizuoka Prefecture, Japan. As of 1 April 2019, the city had an estimated population of 30,678 in 13,390 households, and a population density of 84 persons per km2. The total area of the city was 363.97 square kilometres (140.53 sq mi).

The Izu peninsula is a large mountainous peninsula with a deeply indented coastline to the west of Tokyo on the Pacific coast of the island of Honshu, Japan. Formerly known as Izu Province, Izu peninsula is now a part of Shizuoka Prefecture. The peninsula has an area of 1,421.24 km2 (548.74 sq mi) and its estimated population in 2005 was 473,942 people. The peninsula’s populated areas are located primarily on the north and east.