Map of Japanese provinces (1868) with Izu Province highlighted
Izu Province (伊豆国 Izu-no kuni) was an old province of Japan in the area of Shizuoka Prefecture on the island of on Honshū. It was also known as Zushū (豆州).
Izu had borders with Sagami and Suruga Provinces.
View of Izu Province, lithograph by Wilhelm Heine, 1856
During the Edo period, the Tōkaidō road passed through northern Izu. Travelers from Edo to Kyoto stopped at the post town (shuku-eki) at Mishima.
In the 1850s, Shimoda was opened to American trade. The first American Consulate in Japan was opened at the temple of Gyokusen-ji in Shimoda.
In the Meiji period, the provinces of Japan were converted into prefectures. The maps of Japan and Izu Province were reformed in the 1870s.
The Izu Peninsula is today the eastern portion of Shizuoka Prefecture. The Izu Islands are considered part of Tokyo.
Mishima taisha was the chief Shinto shrine (ichinomiya) of Izu. 
Media related to Izu Province at Wikimedia Commons